Which value of x solves the equation cos x° = sin (20° + x°), where
0 < x < 90?

answer choices
a.30°
b.35°
c.40°
d.45°
e.55°

when the sin of an angle is equal to the cosine of another angle, then it is implied that the two angles are complementary. This means that the sum of the two angles is equal to 90 degrees. Thus, the equation becomes x + 20 + x = 90; 2x = 90 - 20; x = 35 degrees. Hence the answer to this problem is B. 35