0

ADNAN MUHAMMED

Grade 12,

Courses New

Prove that , (sinX) 3 × sin3X + (cosX) 3 × cos3X =(cos2X) 3

Prove that ,
(sinX)3 × sin3X + (cosX)3 × cos3X =(cos2X)3

Grade:12th pass

1 Answers

Susmita
425 Points
5 years ago
Use the formula
sin3x=(3sinx-sin3x)/4
and cos3x=(3cosx+cos3x)/4
also cos3(2x)=(3cos2x+cos6x)/4
Put the first two formula in the given expression.you will get
(3sinxsin3x-sin23x+3cosxcos3x+cos23x)/4
Put 3sinxsin3x+3cosxcos3x=cos(3x-x)=cos2x
And cos23x-sin23x=cos(2.3x)=cos6x.
and see you will get the ans.
 

Think You Can Provide A Better Answer ?

Other Related Questions on Trigonometry

View all Questions »

ASK QUESTION

Get your questions answered by the expert for free

Answer and earn gift vouchers

Win Gift vouchers upto Rs 500/-

View courses by askIITians

Design classes One-on-One in your own way with Top IITians/Medical Professionals

Click Here Know More

Complete Self Study Package designed by Industry Leading Experts

Click Here Know More

Live 1-1 coding classes to unleash the Creator in your Child

Click Here Know More

a Complete All-in-One Study package Fully Loaded inside a Tablet!

Click Here Know More