4
4
COS α
+
If
sina
= 1, then prove that
cos?B sin’B
cos B sinº B
= 1
cosa sin
sina
+
Answers
Answered by
0
Answer:LHS=cos
2
A+cos
2
B+2cosAcosB+sin
2
A+sin
2
B−2sinAsinB
(cos
2
A+sin
2
A)+(cos
2
B+sin
2
B)+2cosAcosB−2sinAsinB
2+2cosAcosB−2sinAsinB
2+cos(A+B)+cos(A−B)−cos(A−B)+cos(A+B)
2+2cos(A+B) (∴cosx=2cos
2
2
x
−1)
2+2[2cos
2
2
(A+B)
−1]
2+4cos
2
2
(A+B)
−2=4cos
2
2
(A+B)
=R.H.S
Hence proved.
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