Question

Calculate cosine to two decimal places

Answer 1

The answer is C. -0.07.

Answer 2

Final answer is approx -0.07.

Explanation:

We have been given a picture of the triangle whose sides are 7, 8 and 11.

Apply cosine formula to find the value of
`\cos\left(\theta\right)`.

`a^2=b^2+c^2-2\cdot b\cdot c\cdot\cos\left(a\right)`

`11^2=7^2+8^2-2\cdot 7\cdot 8\cdot\cos\left(\theta\right)`

`121=49+64-112\cdot\cos\left(\theta\right)`

`121=113-112\cdot\cos\left(\theta\right)`

`121-113=-112\cdot\cos\left(\theta\right)`

`8=-112\cdot\cos\left(\theta\right)`

`(8)/(-112)=\cos\left(\theta\right)`

`-0.0714285714286=\cos\left(\theta\right)`

Hence final answer is approx -0.07.