6.05 Double angle identities

Interactive practice questions

Simplify $\cos^2\left(15^\circ\right)-\sin^2\left(15^\circ\right)$cos2(15°)−sin2(15°).

Easy

1min

Simplify $2\sin22.5^\circ\cos22.5^\circ$2sin22.5°cos22.5°.

Easy

< 1min

Simplify $2\cos^2\left(157.5^\circ\right)-1$2cos2(157.5°)−1.

Easy

1min

Find the exact value of $\sin67.5^\circ$sin67.5°.

Express your answer with a rational denominator.

Easy

4min