Answer:
x° = 149°
Step-by-step explanation:
According to the <u>Triangle Sum Theorem</u>, the sum of the measures of the angles in every triangle is 180°. Since we are given two angles with measures of m < 86° and m < 63°, then the third angle must be:
m < 86° + m < 63° + m < (angle 3) = 180°
149° + m < ? = 180°
Subtract 149° from both sides to solve for m < (angle 3)
149° - 149° + m < (angle 3) = 180° - 149°
m < ? = 31°
Therefore, the measure of the third angle is 31°.
To find x°, we can reference the <u>Triangle Exterior Angle Postulate</u>, which states that the measure of an exterior angle of a triangle is equal to the sum of the measures of the remote interior angles.
In other words, the measure of x° = m < 86° + m < 63°
x° = 149°
By the way, m< (angle 3) and x° are also supplementary angles whose sum equal 180°:
x° + m < (angle 3) = 180°
149° + 31° = 180°
Answer is below..............
Essentially, what we need to do here is prove that BE=EC, BE=CB, and.or CE=BC therefore making it isosceles. With ∠AEC=∠DEB, we know AE=DE, so EC=EB (the points go in order). Therefore, as EC=EB, BEC is isosceles (it has at least 2 equal sides).
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