i just wanted to say how much i appreciate your channel! i just started a harder math program and your videos really helped. thank you!
@GrantOakes
Жыл бұрын
5:45 mark, 95 degrees would have the ladder falling over away from the building, assuming that 90 degrees is straight up and 95 degrees is an obtuse angle. YES, I AM paying attention!
@JohnnyHughes1
9 ай бұрын
Correct.. and not possible in a right triangle. The two OTHER angles in a right triangle add to 90, so both must be 90 or less.
@devonwilson5776
Жыл бұрын
Greetings. The length of the ladder that is required to reach 90' up the wall when the foot of the lader makes a 75 degree angle with the ground is 93.2 feet. The solution is obtained by using trigonometric principle of Sin theta, theta being the angle between the base and the hypotenuse, equals the opposite side of a right angled triangle over its hypotenuse. From the details given, we need to find the length of the hypotenuse, the length of the ladder. We will assume that the length of the ladder is represented by X. Now, we have Sin 75 degrees equals 90/X, and XSin75=90. Moving on, X=90/Sin 75, X=90/.96592582=93.1748562=93.2 feet, rounded. Lovely.
@tcz7742
Жыл бұрын
1973, first year university, I bought an HP-35 . The gold standard of the day . $500.
@glennwright9747
9 ай бұрын
@@tcz7742I’m still using my HP32S
@GrantOakes
Жыл бұрын
Changed my mind, I'm taking the elevator! 9 stories up, on a ladder? You're NUTS!
@glenwardgross366
Жыл бұрын
John can you do a video on how to figure out Sin 75 degree without the charts in the back of the math books and calculator? Also, how do you calculate pie by paper?
@terryjohinke8065
Жыл бұрын
Got it! ( ex Maths teacher and twin bro. was a surveyor)- answer is 93'2"
@tonidozier4573
Жыл бұрын
My drawing and problem setup was correct (I was thrilled), especially since I haven’t been exposed to this info in several years. I used radians (why?) when I got Sin 75°.
@user-zu6qn9ux9n
Жыл бұрын
Answer: A bloody big one!
@russelllomando8460
Жыл бұрын
We had to walk uphill, both ways... Got it all, diagram, formula, and soh, cah, toa, just didn't have the calc for the sin. I'm happy I got as far with my knowledge. Great problem.
@renebouman7513
Жыл бұрын
Those lovely old days, last week I discovered my old high school book of tables, never used it again after I got my first calculator in '73
@hotwireman49
10 ай бұрын
Oh joy! Rapture! I love you!!❤❤❤❤ I subbed. Thank you!!
@GrantOakes
Жыл бұрын
I did it by taking the tangent of the opposite angle, 15 degrees X 90 squared, adding to square of 90 nad then the square root of that and you get a tad over 93'.
@Geoff_G
Жыл бұрын
Well, there's about 2' overlap in each fly section of the ladder. The longest fly section is generally about 20". And of course, there are the extra 4 rungs about the step off point. So, a 120' six fly section extension ladder. And that ladder would need some amazing tormentor poles.
@JackSprat-vk1nz
10 ай бұрын
Is the adjacent side approximately 24.11ft?
@fionam3554
Жыл бұрын
That 30* angle is dangerous. Center of gravity is far from the foot of the ladder and the force of gravity on it is DOWN. The feet are going to slip unless you anchor the heck out of them (like a fire truck ladder, the truck won't slide) and the leverage is going to stress the heck out of the ladder material- aluminum likely holds, wood likely doesn't and snaps if the person is heavy)
@glenwardgross366
Жыл бұрын
Safety 1st, 2nd, 3rd. If you do not understand the 3 rules then read them again. If you do not understand the rules then you need to leave now. Please if you need a ladder to work then follow the 75 rule because it will save your life. I think John has lost it..... A 90 ft building is basically a 9 story building. What home improvement store carries ladders this size? We are looking at a 100' ladder placed at a 75 degrees opposite the 90 degree right angle base with 15 degree @ the top angle. Home improvement stores sell ladder that are two sectioned. John's ladder would have to have 10 sections to reach the top of the 90' building. Two piece ladders are rated @ 300 lbs. each section is 10 ft. @ 10 sections what would the safe lbs for someone brave enough to climb the ladder to put up the Xmas lights on the building. Just for fun. Blessing
@JackSprat-vk1nz
10 ай бұрын
I tried to follow along but my calculator kept giving me .12 or 1.2 The problem was you said 90 divided by sin 75 but on my phone the 75 has to be put in before the sin button.
@dakotaiv
Жыл бұрын
I'm using the Sine (SIN) function in Excel. In Excel, SIN(75) = -0.387781. What am I doing wrong?
@robomonkey6219
Жыл бұрын
You're using radians instead of degrees.
@devonwilson5776
Жыл бұрын
Greetings. Funny that you would say that. I was using one calculator and turned up with the same value. When I divided 90 by that figure the answer obtained was ridiculously high and so I was led to think that something was wrong. In addition, the minus was a tip off. Thereafter, I checked another calculator and received a different figure that was more palatable and decided to go with the more reasonable solution.
@pixelpatter01
Жыл бұрын
If you have ever climbed a 90 foot ladder you are in a small group of human beings.
@mikemassey7403
Жыл бұрын
You got that right. I have enough sense to NOT climb the damn thing.
@juergenilse3259
Жыл бұрын
I wouldn't do that.If needed, i would pay someone for it ...
@mda7763
9 ай бұрын
Important note You cannot enter Sin(75) into your calculation The correct way is 75Sin. Enter 75 then hit the sin key
@stevemccready6776
Жыл бұрын
The correct answer is anything over 40' is not Osha approved
@renolds531
Жыл бұрын
A 90 foot ladder is needed to reach 90 feet, irrespective of the angle.
@mda7763
9 ай бұрын
Wrong
@lakeireland
Жыл бұрын
After living in the South for 23 years, I know the answer a 70’ ladder with a 20ft ladder tied to it. (Seriously, don’t do that, you’ll break your head )
@GrantOakes
Жыл бұрын
hahahahahaha! You even added that you're from the South, had me in stitches!
@ganggreen9012
9 ай бұрын
You need a 90' ladder on top of a 3' table.
@roy40ss
Жыл бұрын
A much easier way to remember is “see old Harry, catch a herring, trawling off America” 😀
@StephenRayWesley
Жыл бұрын
93.17
@juergenilse3259
Жыл бұрын
... is a little bit to short(as the exact answer is 93.1748...). Better do not round correctly but always round up in this case ...
@mikechappell4156
Жыл бұрын
Was SOH-CAH-TOA supposed to be easy to remember or something. Really didn't need a trick to remember sine=opposite/hypotenuse, cosine=adjacent/hypotenuse, tangent=opposite/adjacent, if I did, SOH-CAH-TOA wouldn't be it.
@pesky4649
Жыл бұрын
A little over 93 ft.
@JohnnyHughes1
9 ай бұрын
Scientific Calculators ..heh. Now do it with a Sin table and slide rule.😊
@generalmanagerformays587
Жыл бұрын
I actually got 93.1773 but rounded it up to 93.18
@juergenilse3259
Жыл бұрын
The exact value is 90*(sqrt(6)-sqrt(2)).You can get this result, if you know, that sin(75°)=(sqrt(2)+sqrt(6))/4 ...
@Jabba1973
Жыл бұрын
This result seems to indicate you are using an angle slightly below 75° (74.9943928798895° to be more specific)
@simmo5071
Жыл бұрын
93’
@camdeskjockey2355
Жыл бұрын
Though I got the right answer, the better answer is get a boom truck. LOL
@muchomacho2504
7 ай бұрын
Back in MY day, calculators were called "slide rules"
@TheRitchieLeeShow
Жыл бұрын
A very long ladder😂
@juergenilse3259
Жыл бұрын
better longer than to short??? The you may prefer a 250 feet ladder?
@generalmanagerformays587
Жыл бұрын
93.18 ft
@harrymatabal8448
8 ай бұрын
Ok a ladder is in the shape of a rectangle with each rung parallel to each other and at 90^0 to the 2 uprights. I can't see a ,75^0. Please clear my confusion. By the way I hope you didn't fall from a ladder and bump your head on a stone. Ok
@davidloewen5528
Жыл бұрын
I doubt anyone makes ladders in increments of less than one foot. Probably should have gone with metres, might have avoided that OSHA comment. That one rules.
@Kerbeygrip
Жыл бұрын
I live in Europe what are ft?
@djholro
Жыл бұрын
1 ft = 30 cm 90 ft = 27 m
@juergenilse3259
Жыл бұрын
@@djholro No. the exact factor to convert feet to eters is 3.048, so 90 ft is about 29 m and 53 cm.1 ft is about 32.8 cm, not only 30 cm ...
@djholro
Жыл бұрын
@@juergenilse3259 i was just giving a ballpark figure. Accuracy means nothing to someone who can't envision what a foot is. If you want to be more accurate, sure. Use 30.48 cm. That still makes 90 ft = 27.432 m.
@juergenilse3259
Жыл бұрын
@@djholro 3.048 feet are 1 m,1 feet is 1/3.048 m, which is about 0,328 m or 32.8 cm. So 90 feet is about 29,53 m, not only 27.432 m ...
@djholro
Жыл бұрын
@@juergenilse3259 you're using the wrong conversion factor. 1 m = 3.281 ft. That does NOT mean 1 ft = 32.81 cm. Google it.
@notreallydavid
11 ай бұрын
'How long a ladder...?' - no 'of'. Please kick me All best.
@janettweed2701
Жыл бұрын
15 ft
@MathsMadeSimple101
Жыл бұрын
Why on earth would anyone climb a ladder that long.
@ndailorw5079
8 ай бұрын
@MathMadeSimple 101 …to see how it looks and feels to climb up a ladder that’s leaning at a 75° angle up against a wall, or something…? …couldn’t resist.. lol!
@stevedietrich8936
Жыл бұрын
108 Edit: :( I hated trig and basically tuned out, as my answer shows.
@stevenscottoddballz
Жыл бұрын
Steve Demme teaches: "What do you do if you stub your toe badly? You SOH-CAH-TOA. [soak a toe]"
@StephenRayWesley
Жыл бұрын
13728
@juergenilse3259
Жыл бұрын
at least not to short, but a ladder of this length would be very difficult to handle ... 😏
@alastairgreen2077
10 ай бұрын
How long a ladder, not long of a...
@Nikioko
Жыл бұрын
What is 90ft?
@DavidChadderton-g7d
Жыл бұрын
90 feet.😊
@juergenilse3259
Жыл бұрын
A 90 feet ladder reaches only a height of nearly 87 feet (at an angle of 75°), so you have to bypass the last 3 feet without the ladder ...
@DavidChadderton-g7d
Жыл бұрын
@@juergenilse3259 No. A 90 ft ladder stood vertically reaches a height of 90 ft. Cannot climb it without bolting it onto the wall, but chimney ladders are fixed that way, just ask Fred Dinah the Steeplejack.
@juergenilse3259
Жыл бұрын
@@DavidChadderton-g7d It was asked for a ladder standing in an angle of maximal 75° to the ground. that was given as part of the excercise.With a 90 ft ladder standing in an angle of 75°, you reach a height of a little bit less than 87 ft.
@richfrazier8756
6 ай бұрын
Not 90 degrees, 90 feet!
@henkhu100
11 ай бұрын
Why do you make things so difficult? What has the fact that a^2+b^2=c^2 to do with the solution? All these extra things are rather confusing for a lot of students. Just using sin = O/H so sin(75degr) =90/x is enough to find the solution. The rest has nothing to do with finding the answer. Don't make math more difficult than it already is for many people.
@keithschipiour4684
Жыл бұрын
I will figure that out when the govt leaves me a million dollars on 90ft roof and I have to retrieve it.
@timothybloomer4246
Жыл бұрын
"How long of a ladder?". Clearly not an English class.
@MathsMadeSimple101
Жыл бұрын
First.
@keithschipiour4684
Жыл бұрын
I dont care. If ladder does not seem stable at whatever angle ladders position is I am not climbing ladder . It's called common sense math
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