中等MATH-TRIG-012
A vertical pole stands on horizontal ground. From a point 15 m from the foot, the angle of elevation of the top is 40°. The height of the pole is
A. 15 sin 40°
B. 15 tan 40°✓ 答案
C. 15 cos 40°
D. 15 / sin 40°
解說
The 15 m distance is adjacent to the angle of elevation and the height is opposite, so height = 15 tan 40°. Using sine would be correct only if 15 m were the line of sight.