ABC-isosceles (AB = BC). Find angle A if angle B = 70.
| September 8, 2021 | education
An isosceles triangle is a triangle in which the sides are equal.
An isosceles triangle has the following property: the angles at the base of the triangle are equal.
Under the conditions of this problem, this means that the angle A is equal to the angle C.
In addition, it is known that the sum of the angles of any triangle is 180 degrees, which means:
A + B + C = 180.
Since in a given triangle A = C, then:
2A + B = 180.
From here
2A = 180 – B;
A = (180 – B): 2;
A = (180 – 70): 2;
A = 110: 2;
A = 55.
Answer: The degree of the pen of angle A is 55 degrees.
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