CBSE (Arts) Class 11CBSE
Share
Notifications

View all notifications

Prove that Cos 4x = 1 – 8sin2 X Cos2 X - CBSE (Arts) Class 11 - Mathematics

Login
Create free account


      Forgot password?

Question

Prove that cos 4x = 1 – 8sincosx

Solution

L.H.S. = cos 4x

= cos 2(2x)

= 1 – 2 sin2 2x [cos 2A = 1 – 2 sin2 A]

= 1 – 2(2 sin x cos x)2 [sin2A = 2sin A cosA]

= 1 – 8 sin2x cos2x

= R.H.S.

  Is there an error in this question or solution?

APPEARS IN

 NCERT Solution for Mathematics Textbook for Class 11 (2018 to Current)
Chapter 3: Trigonometric Functions
Q: 24 | Page no. 73

Video TutorialsVIEW ALL [1]

Solution Prove that Cos 4x = 1 – 8sin2 X Cos2 X Concept: Trigonometric Functions of Sum and Difference of Two Angles.
S
View in app×