Question

19. Using the formula, sin A= √ 1-cos 2A/2, find the value of sin 30°, it
being given that cos 60°=1/2​

Answer 1

Answer:

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

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

$\sin(30) = \sqrt{1 - {( \frac{ \sqrt{3} }{2}) }^{2} }$

$\sin(30) = \sqrt{1 - \frac{3}{2} }$

$\sin(30) = \sqrt{ \frac{1}{4} } = \frac{ \sqrt{1} }{ \sqrt{4} } = \frac{1}{2}$

$\huge{\mathrm{\underline{\underline\pink{ \sin(30) = \frac{1}{2} }}}}$

hope this helps you