Question

http://tinypic.com/view.php?pic=29bc18l&s=6

Part 1. Use the 25° angle and the sine ratio to find the length of side b to two decimal places.

I put: sin(25)=a/25
Is that right?

Part 2. You can find the length of side a using cos 25° , tan 25° , or the Pythagorean theorem. Find the length of side a to 2 decimal places using one of these methods.

Answer 1

sine is the ratio of the side opposite the angle to the hypotenuse. Cosine is the adjacent side divided by hypotenuse. In your pic, the side with length "a" is adjacent to the 25 degree angle, so you have the incorrect expression. cos(25) = a/25.

However, for part 1, you really didn't want to solve for "a"... you needed to solve for "b".

sin(25) = b/25 --->> then solve for b.

For part 2, you can use Pythagorean theorem (25^2 - b^2 = a^2, then solve for a), or you can use that cosine expression I listed above. cos(25) = a/25.

Or, since tangent is "opposite over adjacent", you could use tan(25) = b / a and substitute in the value you found for "b" from the first part of the problem.

Answer 2

b is -3.31, right?

Answer 3

I don't think so...

I get sin(25) to be 0.422, then b is 25 * 0.422.

Make sure your calculator is set on degrees, not radians.

Answer 4

oh, i see

Answer 5

so 25^2-10.5^2=a^2

Answer 6

which equals 514.75

Answer 7

so a is 22.69