range of cos^2A+cos^2(120-A) is
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Answer:
3/2p
Step-by-step explanation:
cos
2
A+cos
2
(120
∘
+A)+cos
2
(120
∘
−A)=cos
2
A+
2
1
(1+cos(240
∘
+2A))+
2
1
(1+cos(240
∘
−2A))
=cos
2
A+1+
2
1
(cos(240
∘
+2A)+cos(240
∘
−2A))
=1+cos
2
A+
2
1
(2cos240
∘
cos2A)
=1+cos
2
A−
2
1
(2cos
2
A−1)
=1+
2
1
=
2
3
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