In a triangle ABC, the angle B is 90 degrees CC1 bisector if CC1 20 cm BC1 is 10 cm then the outer angle

In a triangle ABC, the angle B is 90 degrees CC1 bisector if CC1 20 cm BC1 is 10 cm then the outer angle at the vertex A is equal.

Since according to the condition in the triangle ABC the angle B is straight, then such a triangle is right-angled.

Let’s draw the bisector CC1, then the angles BCC1 = ACC1.

Consider a triangle ВСС1, where ВС1 = 10 cm leg, which is half the hypotenuse CC1 = 20 cm, then the angle ВСС1 = 30.

Therefore, the entire angle ACB = 2 * 30 = 60. And the angle A is equal to 90 – 60 = 30 °.