Step {{ step }} of {{ totalSteps }}

Combine angles

Find two standard angles that add or subtract to make {{ s1.targetAngle }}°.

{{ s1.slots[0] }}°
{{ s1.slots[1] }}°
=
{{ s1.targetAngle }}°

Build the formula

Drag the terms to complete the {{ s2.formulaName }} formula.

{{ s2.sign }}

Slide to merge

Discover the double-angle formula by setting equal to .

Tap to simplify

Apply identities to simplify the expression.

=

Mastered!

You've successfully built, merged, and simplified complex trigonometric identities.