I need all the work
2007-03-09 16:23:10 · 4 answers · asked by jinko 2 in Science & Mathematics ➔ Mathematics
1/4(cos12xcos4x)
= (1/4){(1/2)[cos(12x-4x) + cos(12x+4x)]}
=(1/8)(cos8x+cos16x)
2007-03-09 16:33:57 · answer #1 · answered by datz 2 · 0⤊ 0⤋
Using the formula : cos A + cos B = 2 cos (A+B)/2 cos (A-B)/2
1/4(cos12xcos4x)
= 2/8(cos12xcos4x) (Dividing and multiplying by 2)
= 1/8 (2 cos (16x+8x)/2 cos (16x-8x)/2)
= 1/8 cos16x + 1/8 cos8x
You cannot cancel 1/8 with the angles 8x and 16x. Its against the rules
2007-03-10 00:37:25 · answer #2 · answered by beachblue99 4 · 1⤊ 0⤋
1/4(cos12xcos4x)
=1/4(cos4x(3+1))
=1/4(cos4x.4)
cancelling 4 in the numerator by 4 in the denomenator
=cos 4x
done
2007-03-10 00:28:22 · answer #3 · answered by amrita 2 · 0⤊ 1⤋
mutiply and divide by 2,
1/8(2cos12xcos4x)
using 2cosAcosB = cos(A+B) + cos(A-B),
=>1/8(cos16x + cos8x)
that is in the form of sum.
i think it's ok
bye.
2007-03-10 00:45:07 · answer #4 · answered by Tarun J 2 · 0⤊ 0⤋