三角比question

圖片參考：http://h.imagehost.org/0346/ScreenHunter_01_Jun_03_08_32.gif


http://h.imagehost.org/0346/ScreenHunter_01_Jun_03_08_32.gif

2010-06-03 18:22:22 補充：
請參考意見~!

2010-06-04 08:57:13 補充：
http://img217.imageshack.us/img217/4343/screenhunter03jun040852.gif

Trigonometric Function eg sin,cos,tan,they have to calculate with a angle theta,
it means they have no meanings and values when only sin,cos,tan in the calculation,

so sin(x),cos(x),tan(x),s be the angle,which the angle x must be contain to form a Trigonometric equation

in these case,

sin76-sin16

you can not factorize above equation because sin is a Trigonometric function and not a unknow,if its a unknown,you can factorize,

since
sin76-16 not equal to sin(76-16)
sin(a-b) = sin(a)cos(b)-cos(a)sin(b)

so therefore

sin(76-16) = sin76cos16-cos76sin16

so that,
sin76-sin 16 not equal to
sin76cos16-cos76sin16


in your case

sin theta = sin76 - sin16

theta = sin^-1(sin76-sin16)


sin(a-b) = sin(a)cos(b)-cos(a)sin(b)

sin76 - sin16

= 2cos[(76+16)/2] sin[(76-16)/2]

= 2 (cos46) sin30

= 2 (cos46) (1/2)

= cos46

= sin44

因為sin 76 - sin 16 並唔等於
sin(76 - 16)

而係等於0.970295... - 0.275637...
跟住用反三角函數 黎計番theta 既值