Question

Find the missing value to the nearest hundredth.
cos ___ =9/20

Answer 1

The missing value is 63.26°.

Explanation:

Let the missing value be x.

The given equation is

`\cos x=(9)/(20)`

Taking cos⁻¹ on both the sides.

`\cos ^(-1)(\cos x)=\cos ^(-1)((9)/(20))`

`x=\cos ^(-1)((9)/(20))`
`[\because \cos^(-1)(\cos x)=x]`

`x=\cos ^(-1)(0.45)`

`x=63.2563160496^(\circ)`

`x\approx 63.26^(\circ)`

Therefore the missing value is 63.26°.

Answer 2

`\cos\theta= (9)/(20) \\ \\\theta=\arccos (9)/(20) =63.26^o`