Question

sin 2 A = 2 sin A Cos A is true when A is equal to (a) 0° (d) All of these (c) 45° (b) 30°​

Answer 1

0°

Step by Step

sin2A=2sinA

⇒2sinAcosA=2sinA

⇒2sinA(cosA−1)=0

⇒sinA=0,cosA−1=0

⇒sinA=0,cosA=1

sinA=0⇒A=0,π,2π

cosA=1⇒A=0,2π

∴A={0,π,2π}∩{0,2π}

={0,2π}

Hence A=0

Answer 2

option A

0 degree is the right answer for sure.

according to me this is from lesson intro to trigonometry