CBSE Class 10 Sample Paper for 2024 Boards - Maths Standard

Class 10
Solutions of Sample Papers for Class 10 Boards

## (a) sec A                        (b) sin A                   (c) cosec A               (d) cos A

This question is similar to Example 10 - Chapter 8 Class 10 Introduction to Trignometry

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### Transcript

(sec A + tan A)(1 β sin A) We write everything in terms of sin A and cos A = (1/cosβ‘γ π΄γ +" " sinβ‘γ π΄γ/cosβ‘γ π΄γ ) (1 β sin A) = ((1 +γ sinγβ‘γ π΄γ)/cosβ‘γ π΄γ )(1 β sin A) = ((1 +γ sinγβ‘γ π΄) (1 βγ sinγβ‘γ π΄)γ γ)/(cosβ‘ π΄ ) = ((12 βγ sin^2γβ‘γ π΄) γ)/( cosβ‘γ π΄γ ) = ((π βγ γπππγ^πγβ‘γ π¨) γ)/( πππβ‘γ π¨γ ) = cosβ‘γ2 π΄γ/( cosβ‘γ π΄γ ) = cos A cos2 A + sin2 A = 1 cos2 A = 1 β sin2 A β΄ 1 β sin2 A = cos2 A So, the correct answer is (d)