Question

Find the value of sin 330cos 120 +cos 210 sin 300

Answer 1

Answer : 1

Explanation :

Sin330 = sin(360-30)= -sin30

cos120= cos(90+30)=-sin30

cos210=cos(180+30)=-cos30

sin300=sin(270+30)=-cos30

Now,

sin 330cos 120 +cos 210 sin 300

=(-sin30)(-sin30)+(-cos30)(-cos30)

= sin²30+cos²30

= 1

[ since, sin²A+cos²A=1]

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