Answer:
angle D equal to 3 X + 20 + 7 x minus 3 x
=90 degree equal to x minus 3 X + 20
7 X equal to 70 X equal to 10
The answer for number 3 is 3.c
As isosceles triangle has two congruent sides with a third side
<span>that is the base. </span>
<span>A base angle of an isosceles triangle is one of the angles formed by </span>
<span>the base and another side. Base angles are equal because of the </span>
<span>definition of an isosceles triangle. </span>
<span>A picture would probably help here: </span>
<span>A </span>
<span>. </span>
<span>/ \ ABC = ACB = 39 degrees </span>
<span>/ BAC = ??</span>
<span>._______________. </span>
<span>B C </span>
<span>base </span>
<span>ABC is the isosceles triangle. AB is congruent to AC. Angle ABC </span>
<span>is congruent to angle ACB. These are the base angles. </span>
<span>Triangle is a convex polygon with three segments joining three non-collinear points. Each of the three segments is called a side, and each of the three non-collinear points is called a vertex. </span>
<span>Triangles can be categorized by the number of congruent sides they have. For instance, a triangle with no congruent sides is a scalene triangle; a triangle with two congruent sides is an isosceles triangle; a triangle with three congruent sides is an equilateral triangle. </span>
<span>Triangles can also be categorized by their angles. For instance, a triangle with three acute interior angles is an acute triangle; a triangle with one obtuse interior angle is an obtuse triangle; a triangle with one right interior angle is a right triangle; a triangle with three congruent interior angles is an equiangular triangle. </span>
<span>One property of a triangle is that the sum of the measures of the three interior angles is always 180 degrees (or pi radians). In addition, the exterior angle of a triangle is the supplement of the adjacent interior angle. The measure of the exterior angle is also the sum of the measures of the two remote interior angles.</span>
