From the information given in the figure, prove that PM=PN= √3×a
PQ=QR=PR=a
=ΔPQR is equilateral
QS=SR=½ QR
QS=a/2
PS is altitude of Δ
=PS=√3/2 a (By Pythagoras Theorem)
Now ,MS=MQ+QS
=a + a/2
MS = 3a/2
Now, ΔPMS is right angled
By Pythagoras theorem,
PM2=MS2+RS2
=(3a/2)2+(√3/2a)2
=(9a2+3a2)/4
PM2 =12a2/4=3a2
so PM=√3a
Since figure is symmetrical, we can prove in the same way for PN
=PM=PN=√3a
Hence Proved