Home
Class 12
MATHS
Find the value of cos(2pi)/7+cos(4pi)/7+...

Find the value of `cos(2pi)/7+cos(4pi)/7+cos(6pi)/7`

Text Solution

Verified by Experts

`S=cos""(2pi)/(7)+ cos ""( 4pi)/(7) +cos""(6pi)/(7)`
`(sin""(3(pi)/(7)))/(sin""((pi)/(7)))cos""((pi)/(7)+(3pi)/(7))=(2sin((3pi)/(7))cos((4pi)/(7)))/(2sin((pi)/(7)))`
`=(sin((7pi)/(7))-sin((pi)/(7)))/(2sin((pi)/(7)))=-(1)/(2)`
Promotional Banner

Topper's Solved these Questions

  • TRIGONOMETRIC RATIOS AND TRANSFORMATION FORMULAS

    CENGAGE|Exercise Exercise 3.1|11 Videos

  • TRIGONOMETRIC RATIOS AND TRANSFORMATION FORMULAS

    CENGAGE|Exercise Exercise 3.2|7 Videos

  • TRIGONOMETRIC FUNCTIONS

    CENGAGE|Exercise SINGLE CORRECT ANSWER TYPE|38 Videos

  • TRIGONOMETRIC RATIOS FOR COMPOUND, MULTIPLE, SUB-MULTIPLE ANGLES, AND TRANSFORMATION FORMULAS

    CENGAGE|Exercise Multiple Correct Answers Type|6 Videos

Similar Questions

Explore conceptually related problems

Find the value of cos(2 pi)/(7)+cos(4 pi)/(7)+cos(6 pi)/(7)

Find the value of (cos(2 pi))/(7)(cos(4 pi))/(7)(cos(6 pi))/(7)

If the value of cos((2 pi)/(7))+cos((4 pi)/(7))+cos((6 pi)/(7))+cos((7(pi)/(7)))=-(l)/(2) Find the value of l

the value of (cos pi)/(7)cos(2(pi)/(7))cos(3(pi)/(7)) is

The value of cos(2pi)/7cos(4pi)/7cos6/7pi is a. -1//2 b. \ 1//2 c. \ 1//4 d. 1//8

The numerical value of cos 2pi/7 + cos 4pi/7 + cos 6pi/7 is=........

Find the value of 2cos^(3)((pi)/(7))-cos^(2)((pi)/(7))-cos((pi)/(7))

Find the value of cos^(2)(pi)/(16)+cos^(2)(3 pi)/(16)+cos^(2)(5 pi)/(16)+cos^(2)(7 pi)/(16)