Practicing Success

Target Exam

CUET

Subject

General Test

Chapter

Quantitative Reasoning

Topic

Trigonometry

Question:

If (a2 - b2) sinx + ab cosx = a2 + b2 then find the value of cosθ.tanθ

Options:

\(\frac{a^2-b^2}{2ab}\)

\(\frac{a^2+b^2}{a^2-b^2}\)

\(\frac{a^2-b^2}{a^2+b^2}\)

\(\frac{a+b}{a^2-b^2}\)

Correct Answer:

\(\frac{a^2-b^2}{a^2+b^2}\)

Explanation:

Make sin2θ + cos2θ = 1 form so divide the equation by a2 + b2

\(\frac{a^2-b^2}{a^2+b^2}\)sinx + \(\frac{2ab}{a^2+b^2}\)cosx = 1

P = a2 - b2

H = a2 + b2

B = 2ab

⇒ cosx.tanx = \(\left(\frac{2ab}{a^2+b^2} \right) \left(\frac{a^2-b^2}{2ab} \right)\) = \(\frac{a^2-b^2}{a^2+b^2}\)