In (not shown), m = 90 ° . If a = 8, b = 15, and c = 17, find m correct to the nearest degree.
A)28 °
B)52 °
C)62 °
D)67 °

Question

In  (not shown), m  = 90 ° . If a = 8, b = 15, and c = 17, find m  correct to the nearest degree.
A)28 ° 
B)52 ° 
C)62 ° 
D)67 °

Quizplus · Accepted Answer

According to the Law of Cosines, $a^2 = b^2 + c^2 - 2bc\cos(A)$. Plugging in the values given, we get $64 = 225 + 289 - 510\cos(90^\circ - m)$. Simplifying gives $\cos(90^\circ - m) = -\frac{71}{510}$. Taking the inverse cosine, we get $90^\circ - m \approx 97.6^\circ$, so $m \approx 62.4^\circ$, which rounds to $\boxed{	extbf{(C) }62^\circ}$.

In (Not Shown), M = 90 °