In an isosceles triangle, one of the angles is 120 degrees and the base is 4 cm. Find the height drawn to the side

Given:
ABC – isosceles triangle,
АС – base,
AC = 4 cm,
АН – height,
angle B = 120 degrees,
Find the length of AH -?
Decision:
1) Consider an isosceles triangle ABC. We know that the sum of the degree measures of any triangle is 180 degrees. Hence:
angle A + angle B + angle C = 180;
angle A = angle C = (180 – 120) / 2;
angle A = angle C = 60/2;
angle A = angle C = 30 degrees;
2) Consider a right-angled triangle ANS. In a right-angled triangle opposite an angle of 30 degrees lies a leg, which is half the hypotenuse. Then AH = 1/2 * AC = 1/2 * 4 = 2 (cm).
Answer: 2 centimeters.