CBSE Class 10 Mathematics Basic 2023: question 31(b)

Hints

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Step-by-step solution

Each step shows the marks it earns, as an examiner would award them. Checked by an independent re-solve from the question paper.

1. LHS $=(\sec \theta +\tan \theta )(1-\sin \theta )=\left(\frac{1}{\cos \theta }+\frac{\sin \theta }{\cos \theta }\right)(1-\sin \theta )$

   1 mark

2. $=\frac{(1+\sin \theta )(1-\sin \theta )}{\cos \theta }=\frac{1-{\sin }^2\theta }{\cos \theta }$

   1 mark

3. $=\frac{{\cos }^2\theta }{\cos \theta }=\cos \theta =$ RHS [since $1-{\sin }^2\theta ={\cos }^2\theta$]

   1 mark

Answer: LHS = RHS, hence proved

Revise the chapter

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