# Hi, How do I find the height of the triangle , the triangle is set

1. Jul 14, 2011

Hi,
How do I find the height of the triangle , the triangle is set at 30 degrees and the length is 5 meters any help would be appreciated.

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2. Jul 14, 2011

### Staff: Mentor

Re: Trigonometry

Can you tell us what you know about trig so far? What learning resources are you using?

http://en.wikipedia.org/wiki/Trigonometry

.

3. Jul 14, 2011

Re: Trigonometry

Hi,
I' ve been learning trig using Khan accademy

4. Jul 14, 2011

### Staff: Mentor

Re: Trigonometry

5. Jul 14, 2011

### Staff: Mentor

Re: Trigonometry

Wow, that's a crazy website! So much to learn!!

6. Jul 14, 2011

Re: Trigonometry

Okay I check out the wiki page and Im still a little confused ,This is what I'm thinking, is that I have to use tan = opposite / adjacent because I know the adjacent is 5 meters and I'm figuring that opposite is 90 degrees is this right

7. Jul 14, 2011

### Staff: Mentor

Re: Trigonometry

You are close. The tan(theta) = opposite side from the angle / adjacent side to the angle.

Your angle is the 30 degrees, and the 5 meter side is adjacent to it. So you have:

tan (30 degrees) = opposite side / 5m

Do you have a calculator that has tan(theta) on it? If so, you should be able to figure out the answer now. Post it for us to check...

8. Jul 14, 2011

### Staff: Mentor

Re: Trigonometry

That's the right function to use, but the opposite is the opposite side, the height you want to find.

Let h be the length of the opposite side. Now write an equation that involves the tangent of the angle you know, and the two sides, then solve for the unknown side h.

9. Jul 14, 2011

Re: Trigonometry

Hi,
So I use my calculator I keyed tan 30 / 5 and got 0.115470053 did I calculate this right or was I supposed to put tan 30 * 5 = 2.886751346 0r have I got this completely totally wrong?

10. Jul 14, 2011

### Staff: Mentor

Re: Trigonometry

That value is way off.

Before doing anything with your calculator, write down the equation that I suggested. Then solve for the unknown, and then use your calculator. (Make sure it is in degree mode.)