Q11 of 80 Page 302

Let us determine the value/value of for which 2 cos2 θ – 3 cos θ + 1 = 0 will be true.

Given, 2cos2θ -3cosθ + 1


Need to check the equation is true for different values of theta


⇒ let θ = 0°


⇒ 2cos20° -3cos0° + 1


⇒ cos0° = 1


⇒ 2(1)2 – 3(1) + 1


= 2-3 + 1


= -1 + 1


= 0


Hence, if θ is 0 the given equation will be true


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