 Click to Chat

1800-1023-196

+91-120-4616500

CART 0

• 0

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

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

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

10 months ago
Think You Can Provide A Better Answer ?
Answer & Earn Cool Goodies

Other Related Questions on IIT JEE Entrance Exam

View all Questions »  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