Ron used 121 congruent equilateral triangles with 2 cm side lengths to form one large equilateral triangle. What is the perimete
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Answer:
Identity is verified.
Step-by-step explanation:
We have to verify the identity
To prove any identity we always prove one side(either left hand side or right hand side) of the equation equal to the other side.
In this identity we take the left hand side first
(as we know cos(a+b) = cosa×cosb-sina×sinb)
= - sinx ( Right hand side)
Hence identity is proved.