Question

Trig Functions Quiz, Help please

Answer 1

Answer:

angle C is 67.38⁰

Step-by-step explanation:

Given;

length AB = 36

length AC = 39

length BC = 15

The angle C can be calculated using cosine rule;

$c^2 = a^2 + b^2 - 2ab\times cos(C)\\\\2ab\times cos(C) = a^2 + b^2 -c^2 \\\\cos(C) = \frac{a^2 + b^2 -c^2}{2ab} \\\\cos(C) = \frac{(15)^2 + (39)^2 -(36)^2}{2(15)(39)} \\\\cos(C) = 0.3846\\\\C = cos^{-1} (0.3846)\\\\C = 67.38^0$

Therefore, angle C is 67.38⁰