In an isosceles triangle ABC with base AC, the angle A is 40. Find the remaining angles.

univerkov | June 1, 2021 | education

Given:
△ ABC – isosceles;
AC – base;
∠А = 40 °;
∠B =?
∠C =?
Decision:
Consider △ ABC, it is isosceles. In an isosceles triangle, the angles at the base are equal.
∠С = ∠А = 40 °;
The sum of all the angles of a triangle is 180 °.
∠А + ∠В + ∠С = 180 °;
2 * ∠А + ∠В = 180 °;
∠В = 180 ° -2 * ∠А;
∠В = 180 ° -2 * 40 ° = 180 ° -80 ° = 100 °.
Answer: ∠С = 40 °; ∠В = 100 °.

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