sin780 sin 480 + cos 240 cos 300 is equals to 1 by 2
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Answered by
7
We have,sin780°sin480°+cos240°cos300°=sin2×360°+60°sin360°+120°+cos180°+60°cos360°-60°=sin60°sin120°+-cos60°cos60°=sin60°sin180°-60°-cos60°cos60°=sin60°sin60°-cos60°cos60°=sin260°-cos260°=322-122=34-14=24=12
raminder1:
i have lot physics doubt
which class doubts u clear
but the answer is 1/2
I'm sorry
thank you so much for helping
when u substitute the values of sin 60 and cos 60 we will get the answer
please make me brainliest
kk
then answer another question of mine please it too urgent
I just posted mine
Answered by
4
Answer:
Step-by-step explanation:
given that
sin 780° sin 480°+cos 240°cos 300°
=sin (4*180°+60°) sin(2*180°+120°)+cos(180°+60°)cos(360°-60°)
=sin 60° sin 120° - cos 60° cos 60°
=sin60°sin (180°-60°)-cos60°cos60°
=sin 60°sin 60°-cos 60°cos 60°
= 2*√3 / 2 - 2*1/2
= √3-1
hence proved.
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