Question

9.
E
U-
441
25
?
1
(1) 18
(2) 81
(3) 196
(4) 225​

Answer 1

Answer:

If A =30

∘

cos3A=Acos

3

A−3cosA

cos90

∘

=4(cos30

∘

)

2

−3(cosA30

∘

)

0=4.(

2

3

)=

2

3.

3

0=4.

2×2×2

3

3

−

2

3

3

0=

2

3

3

−

2

3

3

0 =0

LHS = RHS

Hence proved

Answer 2

Answer:

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