Question

Sin40 - cos 70 = root 3 cos 80 prove that

Answer 1

Answer:

sin40 - cos70

= sin140 - sin20

= sin140 - sin160

= 2cos( (140 + 160)/2) sin( (140 - 160)/2 )

= 2cos150 sin(-10)

= -2cos150 sin10

= -2(-cos30) sin10

= 2cos30 sin10

= 2cos30 cos80

= 2(√3 /2) cos80

= √3 cos80

hope it will help you ☺️

Answer 2

Answer:

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Step-by-step explanation:

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