Angle of elevation problem... it's super simple, but the algebra I need help with ^_^

• Feb 12th 2008, 08:12 PM
Melancholy
Angle of elevation problem... it's super simple, but the algebra I need help with ^_^
A ladder leaning against a building makes an angle of 78 degrees with the ground. THe foot of the ladder is 5 feet from the building. How long is the ladder?

Yadda yadda. Okay, a picture came with it, but I already figured out the problem and here is it:

cos(78) = 5/x
.......... = ...???

How do I get x by itself? Could someone please work the problem for me, and then I'll know how to do the rest. Isn't it annoying when you forget the little things? Thanks!
• Feb 12th 2008, 08:17 PM
Jhevon
Quote:

Originally Posted by Melancholy
A ladder leaning against a building makes an angle of 78 degrees with the ground. THe foot of the ladder is 5 feet from the building. How long is the ladder?

Yadda yadda. Okay, a picture came with it, but I already figured out the problem and here is it:

cos(78) = 5/x
.......... = ...???

How do I get x by itself? Could someone please work the problem for me, and then I'll know how to do the rest. Isn't it annoying when you forget the little things? Thanks!

there are many ways to get x by itself. one way:

cos(78) = 5/x

flip both sides

=> 1/cos(78) = x/5

multiply by 5 on both sides

=> 5/cos(78) = x
• Feb 12th 2008, 08:22 PM
Melancholy
Cool dude! Thanks a bunch. So on my calc, I'd key in cos(78) divided by 5 (which comes out to 0.415)? Or am I having a retarded moment...(Thinking)
• Feb 12th 2008, 08:25 PM
Jhevon
Quote:

Originally Posted by Melancholy
Cool dude! Thanks a bunch. So on my calc, I'd key in cos(78) divided by 5 (which comes out to 0.415)? Or am I having a retarded moment...(Thinking)

hehe, you're having a retarded moment, it seems. you'd key in 5 and then the division sign then cos(78)
• Feb 12th 2008, 08:32 PM
Melancholy
Lol, good to know. Okay, so I key in 5/cos(78), just like you said the first time (Wink), and I get 24.048. Would that be the correct answer?

Ever have one of those weeks where you can literally hear your brain frying through your ears? It's a crisp, bancon-like sizzling sound. Not pleasant. But seriously, thanks for putting up with me lol. *continues digging gigantic hole with which to bury homework* (Rock)
• Feb 12th 2008, 08:54 PM
Jhevon
Quote:

Originally Posted by Melancholy
Lol, good to know. Okay, so I key in 5/cos(78), just like you said the first time (Wink), and I get 24.048. Would that be the correct answer?

Ever have one of those weeks where you can literally hear your brain frying through your ears? It's a crisp, bancon-like sizzling sound. Not pleasant. But seriously, thanks for putting up with me lol. *continues digging gigantic hole with which to bury homework* (Rock)

it would be 24.049

but yeah, you got it