Use a calculator to find the function value. Give your answer rounded to seven decimal places, if necessary.
-cos 47° cos 133° - sin 47° sin 133°
A)2
B)0
C)1
D)-1

Question

Quizplus · Accepted Answer

This expression is an application of the cosine addition formula, cos(A + B) = cosA cosB - sinA sinB. Here, A = 47° and B = 133°, so the expression simplifies to cos(47° + 133°) = cos(180°), which equals -1.

Use a Calculator to Find the Function Value