Question

plzz solve questions no.14 ,

Answer 1

Answer:

Step-by-step explanation:

Answer 2

Hey.


Here is the answer .

Given Formula:

$\cos(a) \: = \sqrt{ \frac{1 + \cos(2a) }{2} }$


Also we are given :

cos60° = 1/2


To find : the value of cos30°



Let's take a as 30°.

the putting that in the given formula we get,


$\cos(30) = \sqrt{ \frac{1 + cos(2 \times 30)}{2} } \\ \\ \cos(30) = \sqrt{ \frac{1 + \cos(60)}{2} } \\ \\ \cos(30) = \sqrt{ \frac{1 + \frac{1}{2} }{2} } \\ \\ \cos(30) = \sqrt{ \frac{ \frac{2 + 1}{2} }{2} } \\ \\ \cos(30) = \sqrt{ \frac{ \frac{3}{2} }{2} } \\ \\ \cos(30) = \sqrt{ \frac{3}{4} } \\ \\ \cos(30) = \: \frac{ \sqrt{3} }{2}$



So. the value of cos30° comes to be √3/2.


Thanks