Trigonometrical Equations 1 Question 10

10. If 0x<2π, then the number of real values of x, which satisfy the equation

cosx+cos2x+cos3x+cos4x=0, is (2016 Main)

(a) 3

(b) 5

(c) 7

(d) 9

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Answer:

Correct Answer: 10. (c)

Solution:

  1. Given equation is cosx+cos2x+cos3x+cos4x=0

(cosx+cos3x)+(cos2x+cos4x)=0



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