Question
If $a \cos ^{2} 3 \alpha+b \cos ^{4} \alpha=16 \cos ^{6} \alpha+9 \cos ^{2} \alpha$ is iden-tity, then(A) $a=1$(B) $a=24$(C) $b=1$(D) $b=24$
Step 1
We can rearrange this equation to get $9 \cos ^{2} \alpha+16 \cos ^{6} \alpha=a \cos ^{2} 3 \alpha+b \cos ^{4} \alpha$. Show more…
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