What is the solution of the ncert class 10 chapter introduction of trigonometry exercise 8.2. I don’t know how to solve the question number 2(3) easily and quickly . Choose the correct option and justify your choice sin 2A = 2 sin A is true when A = (A) 0° (B) 30° (C) 45° (D) 60°.
SonuNewbie
Choose the correct option and justify your choice : sin 2A = 2 sin A is true when A = (A) 0° (B) 30° (C) 45° (D) 60°. Q.2 (3)
Share
(A) is correct.
To find the value of A, substitute the degree given in the options one by one
sin 2A = 2 sin A is true when A = 0°
As sin 2A = sin 0° = 0
2 sin A = 2 sin 0° = 2 × 0 = 0
or,
Apply the sin 2A formula, to find the degree value
sin 2A = 2sin A cos A
⇒2sin A cos A = 2 sin A
⇒ 2cos A = 2 ⇒ cos A = 1
Now, we have to check, to get the solution as 1, which degree value has to be applied.
When 0 degree is applied to cos value, i.e., cos 0 =1
Therefore, ⇒ A = 0°