Dr. J's Maths.com
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Trigonometry - Further trigonometric identities - double angles.
Test Yourself 1.


 

The results required for these further identities are:

sin (2A) = 2sin A cos A

cos (2A) = cos2 A - sin2 A

OR: cos (2A) = 2cos2 A - 1

OR: cos (2A) = 1 - 2sin2 A

Simplifying double angles.    
     
     
     
     
     
     
Identities with double angles.

15. (i) Show that

.

(ii) Hence evaluate in the simplest exact form.

Answer.1/(2+√3).