Question

Look at the figure shown below: Which step should be used to prove that point A is equidistant from points C and B?

Answer 1

Combine points A with C and A with B. Consider ΔABD and ΔACD:

1. AD is common side, then AD\cong AD;

2. CD\cong BD - given in the diagram;

3. \angle ADB\cong \angle ADC .

By SAS Postulate, \triangle ABD\cong \triangle ACD . Congruent triangles have congruent corresponding sides and congruent corresponding angles, so AC\cong AB .

From this proof you can see that correct choice is option D (In triangles ABD and ACD, two sides and an included angle are equal.)

Explanation: