Lets imagine the shape
M
/\
/ | \
/ | \
/ | \
P /___ |___\ N
O
Now in If we take â†MOP and â†MON
As MO ⊥ NP so â MON=â MOP
NO=NP (given)
And MO is a common side
so by side angle side rule of congruency
â†MOP and â†MON are congruent
so MP is congruent to MN