Question

Please help me with this

Answer 1

`(√(51) )/(10)`

Explanation:

Using the Pythagorean identity

sin²x + cos²x = 1 ⇒ cosx = ±
`√(1-sin^2x)`, hence

cosΘ =
`√(1-(7/10)^2)`

=
`\sqrt{1-(49)/(100) }`

=
`\sqrt{(51)/(100) }`

=
`(√(51) )/(√(100) )` =
`(√(51) )/(10)`