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
        
2cosπ/13 cos9π/13+cos3π/13+cos5π/13= 
Please explain fully And in detail manner 
11 days ago

Answers : (1)

Arun
16262 Points
							
2cos(π/13).cos(9π/13)+cos(3π/13).cos(5π/13) = 0 
use the formula, 
2cosC.cosD = cos(C+D)+cos(C-D)
LHS = cos(π/13+9π/13)+cos(9π/13-π/13) + cos(π/13).cos(5π/13) 
= cos(10π/13) + cos(8π/13) + cos(3π/13).cos(5π/13) 
= {cos(10π/13)+cos(3π/13)}+{cos(8π/13) + cos(5π/13)}
use formula, 
cosC + cosD = 2cos(C+D)/2.cos(C-D)/2
= {2cos(π/2).cos(7π/26)}+ {2cos(π/2).cos(3π/26)} 
we know, 
cos(π/2) = 0 
= 0 + 0 = RHS
 
11 days ago
Think You Can Provide A Better Answer ?
Answer & Earn Cool Goodies

Get Extra Rs. 1,590 off

COUPON CODE: SELF10


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

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


Get Extra Rs. 1,590 off

COUPON CODE: SELF10

Ask Experts

Have any Question? Ask Experts

Post Question

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