Question

A right triangle has the hypotenuse c = 12 cm and an angle A = 30°. Find the length of side a, which is opposite angle A. A. 7.4 cm B. 4 cm C. 2.5 cm D. 6 cm

Answer 1

On the one hand we know that sin(30) = 1/2. On the other hand we know that sin(A) = a/c. From these two relations we obtain that 1/2 = a/c <=> 1/2 = a/12 <=> a = 12*1/2 <=> a = 6. So the answer is D. 6cm.