SSC Selection Post 2022 PYQ — Question 73

SSC Selection Post - Graduation Level 2022 - 14 March 2022 - Shift 3 • Quantitative Aptitude • Q73

In △ABC, right angled at B, if cotC = 3, then cosC(sinC+sinA)sinA(cosC−cosA)cosC(sinC + sinA)\over{sinA(cosC-cosA)}is equal to:

Show answer & explanation

Correct answer: D

Explanation

The correct answer is option 4 i.e. 2.

cot C = cot θ = 3 = 3/1

Height (AB) = 1; Base (BC) = 3; Hypotenuse (AC) = √(12 + 32) = √10

cosC(sinC+sinA)sinA(cosC−cosA)cosC(sinC + sinA)\over{sinA(cosC-cosA)}

=310(110+310)310(310−110)=\frac{\frac{3}{\sqrt{10}} \left(\frac{1}{\sqrt{10}} + \frac{3}{\sqrt{10}}\right)}{\frac{3}{\sqrt{10}} \left(\frac{3}{\sqrt{10}} - \frac{1}{\sqrt{10}}\right)}

=310×410310×210= \frac{\frac{3}{\sqrt{10}} \times \frac{4}{\sqrt{10}}}{\frac{3}{\sqrt{10}} \times \frac{2}{\sqrt{10}}}

= 2