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NTA Abhyas 2020
Exam
NTA Abhyas
Year
2020
Subject
Mathematics
Chapter
Trigonometric Equations

NTA Abhyas 2020 · Mathematics · Trigonometric Equations

The number of solution of ^ 2 x + ^ 2 2x = 2 in [0,20] is equal to

The number of solution of cos⁡2x+cos⁡22x=2\cos^{2} x + \cos^{2} 2x = 2 in [0,20]\left[0,20\right] is equal to

Correct answer

7

Step-by-step solution

For this to be true cos⁡2x=1\cos^{2} x = 1 and cos⁡22x=1\cos^{2} 2x = 1
So, x=nπx = n\pi
Since x∈x \in\left[0,20\right], n = 0, 1, 2, 3, 4, 5, 6
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