# AD-bisector of triangle ABC, angle C = 70 degrees, angle BAD = 20 degrees Find angle B.

September 14, 2021 | education

| It is known:

ABC triangle;

AD – bisector of triangle ABC;

Angle C = 70 °;

Angle BAD = 20 °;

Find corner B.

1) Since the bisector divides the angle in half, then we find the angle A. For this, the angle BAD is multiplied by 2.

Angle A = 2 * angle BAD = 2 * 20 ° = 40 °;

2) Consider the triangle ABC.

2 angles are known.

Find corner B.

Angle B = 180 ° – 40 ° – 70 ° = 140 ° – 70 ° = 70 °.

As a result, we got that the angle B = 70 °.

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