The two column proof is written as follows
Statement Reason
AD ≅ BD ≅ CD given
ΔADB and ΔCDB are isosceles Base angles are equal
< A = < C = < ABD = < CBD = x Definition of isosceles triangle.
< ABC = < ABD + < CBD Adjacent angles
< ABC = x + x = 2x Substitution property of equality
< ABC + < A + < C = 180 Sum of angels of a triangle
2x + x + x = 180 Substitution property of equality
4x = 180 Addition property of equality
x = 45 degrees Division property of equality
< ABC = 2x = 2 * 45 Substitution property of equality
< ABC = 90 Definition of right triangle
<h3>What is a right triangle?</h3>
A triangle is said to be a right triangle if one of the angles is 90 degrees. Right angles are angles that are 90 degrees.
The proof required to proof that < B is 90
With the isosceles triangle giving and the equal sides the equation is written as
4x = 180
x = 45
< B has 2x (< ABD + < CBD) these are adjacent angles
< B = 2 * 45
< B = 90
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