PQRS is a rhombus of side 16cm. The diagonal |QS| = 20cm. Calculate, correct to the nearest degree, ∠PQR
-
A.
51o -
B.
64o -
C.
77o -
D.
103o
Correct Answer: Option D
Explanation
cos(alpha) = (frac{10}{16}) = 0.625
(alpha) = cos-1(0.625)
= 51.3o
∠PQR = 2(alpha)
= 2(51.3o)
= 102.6
= 103o