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There are 2 NRICH Mathematical resources connected to Trigonometric identities, you may find related items under Pythagoras and trigonometry.
Broad Topics > Pythagoras and trigonometry > Trigonometric identitiesCan you explain what is happening and account for the values being displayed?
The length AM can be calculated using trigonometry in two different ways. Create this pair of equivalent calculations for different peg boards, notice a general result, and account for it.