Question

How to write a two column proof for number 38

Answer 1

1.- We are given that:

`\angle B\cong\angle ACB`

therefore:

`AB\cong AC.`

2.- Recall that a condition that must be satisfied for three lengths to be the sides of a triangle is that the sum of any pair of lengths is greater than the other length, therefore:

`AD+AC>CD.`

3.- Substituting AC for AB, using the congruence statement in point number 2, we get:

`AD+AB>CD.`