Question

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

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

Answer 1

Answer: (D)

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