Question

Write the product as a sum. 13 sin (x/2) cos (x/4)

The answer I keep getting is 1/2 (sin(3x/4)+sin(x/4)) Is this wrong? or can it be simplified further as 1/2sinx??

Answer 1

@inkyvoyd

Answer 2

?

Answer 3

Sorry, I forget product-sum formulae as well
@FoolForMath

Answer 4

@Callisto

Answer 5

The product sum formula is sinUcosV= 1/2(sin(U+V)+(sin(U-V)))

Answer 6

\[1/2[\sin(x/2+x/4)+\sin(x/2-x/4)]\]

Answer 7

But the answer I get from that is incorrect??

Answer 8

\[1/2[\sin(3x/4)+\sin(x/4)]\]

Answer 9

You should multiply by 13

Answer 10

what about 13?

Answer 11

ohhhhhhh so 13/2 should be in the front? wow I can't believe I missed that

Answer 12

The 13 that was in fron of the product in the question.

Answer 13

yes thank you.

Answer 14

With pleasure.

Answer 15

FYI: There is cool name of this formula: http://mathworld.wolfram.com/ProsthaphaeresisFormulas.html