Question

How do you do number 7 here?

Answer 1

a)

`\sin(2( (5)/(13) )) = 2 \sin( (5)/(13) ) \cos( (5)/(13) )`

b)

`\cos( 2((5)/(13)) ) = { cos }^(2) (5)/(13) - {sin}^(2) (5)/(13)`