SOLUTION: 1.Derive a formula for cos 2A with aid of cos (A + B). 2.Prove that 2 tan x + 2 cot x = 4/sin 2x

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Question 605241: 1.Derive a formula for cos 2A with aid of cos (A + B).
2.Prove that 2 tan x + 2 cot x = 4/sin 2x
Answer by Edwin McCravy(20060)   (Show Source): You can put this solution on YOUR website!
1.Derive a formula for cos 2A with aid of
cos (A + B).
cos(A + B) = cos(A)cos(B) - sin(A)sin(B)

Substitute A for B

cos(A + A) = cos(A)cos(A) - sin(A)sin(A)

Simplifying,

cos(2A) = cos²(A) - sin²(A)

----------------------------

2.Prove that
2·tan(x) + 2·cot(x) = 
2· + 2·

 + 

Get LCD of sin(x)cos(x)









Multiply by 





Edwin
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