Aug 10, 2018 · Let , #X=sin20^circsin40^circsin60^circsin80^circ# #:.X=1/2(sin60^circsin20^circ)(2sin80^circsin40^circ)# Using , #"Product Identity"#

Nov 2, 2015 · (sin 80^@ - sin 10^@)/(sin 80^@ + sin 10^@) = tan 35^@ sin a ± sin b = 2 sin ((a±b)/2) cos ((a∓b)/2) tan A = sin A/cos A (sin 80^@ - sin 10^@)/(sin 80^@ + sin 10 ...

Sep 26, 2016 · This formula can be simplified to -sin60=-sqrt(3)/2 sin20cos80-cos20sin80=sin(20-80)=sin(-60)=-sin60=-sqrt(3)/2

Jun 7, 2018 · Use #cos(90^circ - theta^circ ) = sin (theta^circ ) #. let #theta = 80^circ # #=> cos(10^circ) = sin(80^circ) # ...

Jun 1, 2018 · How do you use an addition or subtraction formula to write the expression as a trigonometric function of one number and then find the exact value given #cos(80)cos(10)-sin(80)sin(10)#? Trigonometry Trigonometric Identities and …

Oct 6, 2017 · Sin(40°)+cos(50°)+sin(80°)-cos(190°) =Sin(40°)+cos(90^@-40°)+sin(80°)-cos(270^@-80^@) =Sin(40°)+sin(40°)+sin(80°)+sin(80^@) =2(Sin(40°)+sin(80°)) =4sin60 ...

Aug 10, 2018 · In triangle ABC, sin A=1/3, sin B=1/5, and b=6, how do you find side a? The length of the base of an isosceles triangle is 30 m. The angle opposite the base measures 32...

Here is an example of using a sum identity: Find #sin15^@#.. If we can find (think of) two angles #A# and #B# whose sum or whose difference is 15, and whose sine and cosine we know.

Oct 8, 2017 · We know, cos C - cos D = - 2 sin(C + D)/2. sin (C - D)/2. Hence, #[ cos 80 - cos 40]/sin 40# #rArr [ - 2 sin (80+40)/2. sin (80-40)/2]/sin 40#

Apr 16, 2018 · sin (200° - 80°)? Find the exact value by using a sum or difference identity. sin (200° - 80 ...