Question

if sin 3 A = cos (A- 10°) and 4A is acute then angle A = ?​

Answer 1

Answer:

A=25

Step-by-step explanation:

using identity ,cos a =sin (90-a)

Answer 2

$\huge\boxed{\color{Magenta} Answer:}$

=> Given that sin4A = cos (A - 10°)

=> Cos 90° - 4A = cos (A - 10)

=> 90° - 4A = A - 10°

=> 90° + 10° = 4A + A

=> 100° = 5A

=> ${\color{Green} A = 20°}$