Question

Using four values of $\theta$ satisfying the equation $8{\cos }^4\theta +15{\cos }^2\theta -2=0$ in the interval $(0,4\pi )$, an arithmetic progression is formed, then:

• A. The common difference of A.P. may be $\pi$.
• B. The common difference of A.P. may be $2\pi$.
• C. Two such different A.P. can be formed.
• D. Four such different A.P. can be formed.

Answer 1

Answer: (A), (D)

Correct answer is (a) The common difference of A.P. may be $\pi$. Correct answer is (d) Four such different A.P. can be formed.