Question

I need help finding x, Ik they should all add up to 180 after x is found. But I’ve been trying different ways and I can’t do it. Someone please help me

Answer 1

x = 42.5

Explanation:

Since the triangle is isosceles then the 2 base angles are congruent.

The base line is a straight angle hence the base angle is

180 - 3x

The sum of the 3 angles in the triangle = 180°, hence

2x - 10 + 180 - 3x + 180 - 3x = 180

- 4x + 350 = 180 ( subtract 350 from both sides )

- 4x = - 170 ( divide both sides by - 4 )

x = 42.5

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2x - 10 = (2 × 42.5) - 10 = 75

180 - 3x = 180 - (3 × 42.5) = 52.5

Sum of 3 angles = 75 + 52.5 + 52.5 = 180° ← correct

Answer 2

42.5

Explanation:

This is an isosceles triangle. The semi-vertical sides are equal. Thus, the angles opposite them are equal. One such angle is (180° - 3x), which is the supplement of the angle 3x.

Thus, the 3 angles of this triangle are (180° - 3x) and (180° - 3x) and (2x - 10°). They must sum up to 180°, as y ou say.

2 (180° - 3x) + (2x - 10°) = 180°

360° - 6x + 2x - 10° = 180°

Combining like terms, we get:

170° = 4x, or x = 170°/4 = 42.5°