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
        Evaluate the following: cos 20°. cos 40°. cos 60°. cos 80°
11 months ago

Answers : (1)

Harshit
31 Points
							
Let
P=cos20.cos40.cos60.cos80
Q= sin20.sin40.sin60.sin80
 
P.Q= (sin20.cos20).(sin40.cos40)(sin60.cos60)(sin80.cos80)
P.Q=  1/16 (sin40.sin80.sin120.sin160)        [sinA.cosA= sin2A/2]
P.Q= 1/16 (sin20.sin40.sin60.sin80)            [sin120=sin(180-60)=sin60  ,  sin160=sin(180-20)=sin20
P.Q= 1/16 Q
P= 1/16
so the value of
cos20.cos40.cos60.cos80=1/16
11 months 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

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


Get Extra Rs. 64 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