The figure below shows a square ABCD and an equilateral triangle DPC.


Jake makes the chart shown below to prove that triangle APD is congruent to triangle BPC.


Statements Justifications

In triangles APD and BPC; DP = PC Sides of equilateral triangle DPC are equal

In triangles APD and BPC; AP = PB Sides of equilateral triangle APB are equal

In triangles APD and BPC; angle ADP = angle BCP Angle ADC = angle BCD = 90° and angle ADP = angle BCP = 90° - 60° = 30°

Triangles APD and BPC are congruent SAS postulate



What is the error in Jake's proof?


He assumes that triangle DPC has all sides equal.


He assumes that triangle APB is an equilateral triangle.


He assumes that the triangles are congruent by the SAS postulate.


He assumes that angle ADC measures 90°.