CBSE Class 10 Mathematics Standard 2025: question 1

Hints

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Step-by-step solution

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1. Write ${\sin }^2\theta =1-{\cos }^2\theta$. Then $7{\cos }^2\theta +3(1-{\cos }^2\theta )=4$, so $4{\cos }^2\theta +3=4$.

   ½ mark

2. This gives ${\cos }^2\theta =\frac{1}{4}$, so $\cos \theta =\frac{1}{2}$ and $\theta =60^{\circ }$. Option (C).

   ½ mark

Answer: $\theta =60^{\circ }$, option (C)

Revise the chapter

• Chapter: Introduction to Trigonometry (notes, formulas, where marks are lost and every past question)