Question

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

Answer 1

B. 0.21

Explanation:

Answer 2

The correct answer option is B. 0.21.

Explanation:

We are to find the value of
`cos \theta` using the law of cosines.

We know that the formula of the cosine rule is given by:

`c ^ 2 = a ^ 2 + b ^ 2 - 2 a b cos C`

So substituting the given values in the above formula:

`10.9 ^ 2 = 5.8 ^ 2 + 10.5 ^ 2 - 2 (5.8) (10.5) cos C`

`118.81=33.64+110.25-121.8cosC`

`118.81 - (33.64+110.25) = -121.8cosC`

`118.81-143.86=-121.8cosC`

`cosC=(-25.05)/(-121.8)`

cos C = 0.21