Question

Express the following as a function of a single angle.
Cos^2(81°) - sin^2(81°)

Answer 1

=
`Cos`(162°)

Explanation:

`Cos^(2)`(81°) -
`Sin^(2)`(81°)

we know that;

`Cos^(2)`(x°) -
`Sin^(2)`(x°) =
`Cos`(2x°)

`Cos^(2)`(81°) -
`Sin^(2)`(81°) =
`Cos`(2 * 81°)

=
`Cos`(162°)