2007-04-22 06:54:58 · 4 answers · asked by Anonymous in Science & Mathematics ➔ Mathematics
because there's an identity for cos(A+B)
cos(A+B)=cos A cos B - sin A sin B
http://www.clowder.net/hop/cos(a+b).html
2007-04-22 07:13:59 · answer #1 · answered by ? 4 · 0⤊ 0⤋
Because cos is a function.
Cos() means take the cos of everyhting in the brackets. Thats just not the same as saying add the cos of the indivudal elements in the bracket.s
2007-04-22 14:02:28 · answer #2 · answered by Anonymous · 0⤊ 0⤋
That's because cos is not a number, it is a function.
The distributive property only applies to numbers.
2007-04-22 14:03:06 · answer #3 · answered by steiner1745 7 · 0⤊ 0⤋
Because it won't give the right answer!
A less facetious reply is to simply say that the distributive property applies to multiplication not to trigonometric functions.
2007-04-22 14:04:04 · answer #4 · answered by mathsmanretired 7 · 0⤊ 0⤋