Question

If sin 3A = 1 and 0 ≤ A ≤ 90, find:(i) sin A (ii) cos 2A

Answer 1

Answer:

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Step-by-step explanation:

Correct option is

A

1

sin3A=1

sin3A=sin90

3A=90

A=30

∘

Now,

cos

2

A

1

−tan

2

A

=

cos

2

30˚

1

−tan

2

30˚

=

(

2

3

)

2

1

−(

3

1

)

2

=

3

1

−

3

4

=

3

4−1

= 1

Answer 2

Answer:

i) 1/2

ii) 1/2

Step-by-step explanation:

sin 3A = 1

sin 3A = sin π/2

3A = π/2

A = π/6 = 30°

Now,

i) sin A = sin 30° = 1/2

ii) cos 2A = cos 60° = 1/2