Question

$4 a^2 \, \sin^2 \left( \frac{3\pi}{4} \right) - 3 [a\, \tan \,225^\circ ]^2 + [ 2a \, \cos \, 315^\circ ]^2$

• A. 0
• B. a
• C. $\sqrt{2a}$
• D. $a^2$

Answer 1

Answer: (D)

$a^2$

Answer 2

Given $= 4a^2 \left( \frac{1}{\sqrt{2}}\right)^2 - 3 [ a \times1 ]^2 + \left[ 2ax \frac{1}{\sqrt{2}} \right]^2$ = $2a^2 - 3a^2 + 2a^2$ = $a^2$