Introduction to Trigonometry
RD Sharma
CBSE
Grade 10
Question:
The value of $(1 + \tan^2 \theta)(1 - \sin \theta)(1 + \sin \theta)$ is:
(a) $1$
(b) $-1$
(c) $0$
(d) $\sec^2 \theta$
Step-by-Step Solution
Key Concept: $(1 + \tan^2 \theta)(1 - \sin^2 \theta) = \sec^2 \theta \cdot \cos^2 \theta = 1$.
$\sec^2 \theta \cdot \cos^2 \theta = 1$. [1.0 Mark]
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🎯 Official CBSE Marking Scheme:
Evaluating product $= 1$: 1.0 Mark
Correct Answer: $1$
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