Question

If A=30°,then show that sin A= underroot(1-cos2A/2)​

Answer 1

Answer:

1/2=√1-1/2/2

taking square of both sides

1/4 =1/4

Answer 2

Answer:

$\sin(a) = \sqrt{1 - \frac{ \cos(2a) }{2} }$

$\sin(30) = \sqrt{1 - \frac{ \cos(60) }{2} }$

by squaring on both sides

${ \ { \sin }^{2} (30) } = 1 - \frac{ \cos(60) }{2}$

$1 - { \sin }^{2} 30 = \frac{ \cos(60) }{2}$

${ \cos }^{2} 30 = \frac{ \cos(60) }{2}$

${ \cos}^{2} 30 = \cos(30)$