Thread: Pretty simple trigonometry but need help

suppose a right angle triangle with angle theta. Given cos(90-theta) = 5/[3(11)^0.5], find the exact value of cos(theta).

Use this and the fact that

thanks iceman i finally see the light haha

I don't think you need to get that complicated. Just use the definitions of sine and cosine within the right triangle with sides x, y, r, and the fact that if one angle is A, the other is 90 - A, and vice versa. So cos(90 - A) = x/r = sin(A) directly.