Question

Use the law of cosines to find the value of cos theta. Round your answer to two decimal places.

Answer 1

well to start

\[\cos^(\theta) = \frac{b^2 + c^2 - a^2}{2bc}\]

a is the side opposite the required angle... theta

b and c are the sides that make the angle

just substitute and calculate

hope it helps

Answer 2

I got 1.24, although none of my answer choices are these. . .

Answer 3

oops, I accidentally added side a. I got 0.22 and that is one of the answer choices

Answer 4

Thank you! :)

Answer 5

well there is an error as the cos of any angle has a range of

-1 <= cos(theta) < = 1

so

\[\cos(\theta) = \frac{5.7^2 + 9.8^2 - 10.2^2}{2 \times 5.7 \times 9.8}\]