sinq = cos(q - 30°) The word "cosine" is an abbreviation for "complement's sine" If the sine of one positive acute angle equals the cosine of another positive acute angle, then the angles are complementary. Therefore: q + (q - 30°) = 90° q + q - 30° = 90° 2q - 30° = 90° 2q = 120° q = 60° sinq =cosq = sinq + cosq = . Edwin