If $cos \theta = \frac{2}{3}$, then $2sec^2 \theta + 2 tan^2 \theta - 6 $ equals :
Answer & explanation
Correct answer: option 2
cosθ = \(\frac{2}{3}\)
{ we know, cosθ = \(\frac{B}{P}\) }
By using pythagoras thorem,
P² + B² = H²
P² + 2² = 3²
P = \(\sqrt { 5}\)
Now,
2 sec²θ + 2tan²θ - 6
= 2(\(\frac{9}{4}\)) + 2(\(\frac{5}{4}\)) - 6
= (\(\frac{9}{2}\)) + (\(\frac{5}{2}\)) - 6
= 1