Question

Sin2A=2SinAcosA is true when A


a) 0°
b) 30°
c) 45°​

Answer 1

Answer:

a) ans. true.

b) ans. false.

c) ans. true.

Step-by-step explanation:

a) Sin2A= 2sinACosA is true when A is 0

sin2*0 = 2*0*1(cos  0 is 1)

hence 0 = 0. hence proved.

b) sin 2*30=2*1/√2*√3/2

⇒ sin 60°=√3/√2. Hence false.

c) sin 90°=2*sin 45°*cos 45°

⇒ 1=2*1/√2*1/√2

⇒ 1=1. hence proved.

Answer 2

The correct answer is a, b and c.

Given: Sin 2A=2 SinA cosA

To Find: The angles which satisfy this equation.

Solution:

Identity: An identity is an equation which is always true. Any value can be substituted it will always hold true.

As we know,

Sin 2A=2 SinA cosA

is an identity so it will hold true for all the angles.

Hence, all the options are correct.

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