Q 13 Find the value of cos220 cos270 sin231 sin259 +sin264 +cos64 sin26 - Maths - Introduction to Trigonometry

Question

Q 13 Find the value of
cos 2 20 °   cos 2 70 ° sin 2 31 °   sin 2 59
° + sin 2 64 ° + cos 64 ° sin 26 °

Shruti Tyagi · Accepted Answer

Dear student,

Assuming the question is  cos220+cos270sin231+sin259+sin264+cos64
sin26 and solving furtherWe havecos220+cos270sin231+sin259+sin264+cos64
sin26=cos220+cos290-20sin231+sin290-31+sin264+cos64
sin90-64=cos220+sin220sin231+cos231+sin264+cos64
cos64          --[using sin (90-θ)=cosθ and cos(90-θ )=sinθ ]=11+sin264+cos264                   --[using sin2θ+cos2θ=1]=1+1                                           --[using sin2θ+cos2θ=1]     =2

Regards

Q.13. Find the value of cos 2 20 ° cos 2 70 ° sin 2 31 ° sin 2 59 ° + sin 2 64 ° + cos 64 ° . sin 26 °

Q.13. Find the value of
$\frac{\cos^{2} 20 ° \cos^{2} 70 °}{\sin^{2} 31 ° \sin^{2} 59 °} + \sin^{2} 64 ° + \cos 64 ° . \sin 26 °$