 ×     #### Thank you for registering.

One of our academic counsellors will contact you within 1 working day.

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
```
cos 20 cos40 cos 60 cos 80=1/16 pfjiernhefjnngfjnjrfgnjrgf
cos 20 cos40 cos 60 cos 80=1/16pfjiernhefjnngfjnjrfgnjrgf

```
4 months ago

```							Welcome to askiitianscos20 cos40 cos60 cos80= 1/16LHS=cos20 cos40 1/2 cos80 (cos60 = 1/2)multiply nd divide by 21/4 (2 cos20 cos40 cos80)1/4 (cos(20+80)+ cos(20-80)) cos40 (2cosa cosb= cos(a+b) + cos(a-b))1/4 (cos(-60)+ cos(100)) cos401/4(1/2 + cos100)cos401/8 cos40+ 1/4 (cos40 cos100)multiplt nd divide by 22/2(1/8 cos40) + 1/8(2 cos40 cos100)1/8 cos40+ 1/8 (cos140+ cos(-60)) (2cosa cosb= cos(a+b) cos(a-b))1/8 cos40+ 1/8 cos140 + 1/16 (cos60= 1/2)1/8(cos40+cos140) + 1/161/8(2 cos90 cos(-50)) + 1/16 (as above identity)cos90= 01/16= r.h.shence proved........Thanks
```
4 months ago
Think You Can Provide A Better Answer ?

## Other Related Questions on Trigonometry

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

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