Question

Given sin 0 and angle 0 is in Quadrant II, what is the exact value of cos 0 in

simplest form? Simplify all radicals if needed.

Answer 1

sin = 3/7

1 = sin²0 + cos²0

cos²0 = 1 - 9/49

cos²0 = 40/49

cos0 = √(40) / 7

since its in Quadrant 2 the sin is positive and cos is negative

cos0 = - √(40) / 7