In an acute-angled triangle abc ac = bc, the angle c is 80 degrees, ad is the height drawn from the vertex a.

In an acute-angled triangle abc ac = bc, the angle c is 80 degrees, ad is the height drawn from the vertex a. Find the degree measure of the angle dab.

1. Consider the ABS triangle: angle С = 80 °, BP – height, and since AC = BС, then ABС – isosceles, => AB – base and angle A = angle B. 2. Angle A = angle B = (180 ° – angle C °): 2 = (180 ° – 80 C °): 2 = 50 ° 3. Consider a triangle ABD – rectangular, angle B = 50 ° means angle DAB = 180 ° – angle B – angle BAD angle DAB = 180 ° – 90 ° – 50 ° = 40 °
Answer: 40 °