MY CART (5)

Use Coupon: CART20 and get 20% off on all online Study Material

ITEM
DETAILS
MRP
DISCOUNT
FINAL PRICE
Total Price: Rs.

There are no items in this cart.
Continue Shopping
Menu
Grade: 11
        If f(x) = cosx• cos2x •cos4x• cos8x• cos16x , then find derivative at x=π/4
one year ago

Answers : (1)

Arun
22032 Points
							
Dear student
 
First check, cos(45) = 1/2^(1/2)
Cos(2*45) = 0
Cos(4*45) = -1
Cos(8*45) = 1
Cos(16*45) = 1
 
f'(x) at pi/4
 Only one term is left
-2sin 2x cosx cos4x cos8x cos16x
At x = pi/4
= -2 sin90 cos 45 cos 180 cos360 cos720
= -2*[1/2^(1/2)]* (-1)*1*1
\sqrt2
 
Regards
Arun (askIITians forum expert)
one year ago
Think You Can Provide A Better Answer ?
Answer & Earn Cool Goodies


Course Features

  • 731 Video Lectures
  • Revision Notes
  • Previous Year Papers
  • Mind Map
  • Study Planner
  • NCERT Solutions
  • Discussion Forum
  • Test paper with Video Solution


Course Features

  • 51 Video Lectures
  • Revision Notes
  • Test paper with Video Solution
  • Mind Map
  • Study Planner
  • NCERT Solutions
  • Discussion Forum
  • Previous Year Exam Questions


Ask Experts

Have any Question? Ask Experts

Post Question

 
 
Answer ‘n’ Earn
Attractive Gift
Vouchers
To Win!!! Click Here for details