Use a calculator to find the function value to four decimal places.
-cos (-418°)
A)0.5299
B)0.8829
C)-0.8480
D)0.0349

Question

Quizplus · Accepted Answer

The cosine function is periodic with a period of 360°, so cos(-418°) is equivalent to cos(-418° + 360°) = cos(-58°). The cosine of -58° is the same as the cosine of 58° due to the even symmetry of the cosine function, and calculating cos(58°) gives approximately 0.5299.

Use a Calculator to Find the Function Value to Four