Answer:
option A is correct
m∠A = 66°
Explanation:
a triangle having two equal sides is called an isosceles triangle
i.e.
m∠C = 57°
m∠B = 57°
m∠A = ?
sum of interior angles in a triangle always add up to 180°
i.e.
m∠A + m∠B + m∠C = 180°
m∠A + 57° + 57° = 180°
m∠A + 114° = 180°
m∠A = 180° - 114°
m∠A = 66°
thus, option A is correct