Answer:
.
See the diagram attached below.
Let the chords be AB and AC with common point A.
AD is the diameter. Join B with D and C with D to form two triangles.
We need to prove that AB=AC.
\begin{gathered}In\ \triangle ABD\ and \triangle ACD;\\Given\ that\ \angle BAD=\angle CAD----(condition\ 1)\\since\ AD\ is\ diameter, \angle ABD=\angle ACD = 90^0\\So\ \angle ADB=\angle ADC--------(condition\ 2)\\AD=AD\ (common\ side)-----(condition\ 3)\\ \\So\ the\ triangles\ are\ congruent\ by\ ASA\ rule.\\Hence\ AB=AC.\end{gathered}
In △ABD and△ACD;
Given that ∠BAD=∠CAD−−−−(condition 1)
since AD is diameter,∠ABD=∠ACD=90
0
So ∠ADB=∠ADC−−−−−−−−(condition 2)
AD=AD (common side)−−−−−(condition 3)
So the triangles are congruent by ASA rule.
Hence AB=AC.
