We have, P=4+i,Q=1+6i,R=−4+3i,S=−1−2i Now, |PQ|=√(4−1)2+(1−6)2=√9+25=√34 |QR|=√(1+4)2+(6−3)2=√25+9=√34 |RS|=√(−4+1)2+(3+2)2=√9+25=√34 |SP|=√(−1−4)2+(−2−1)2=√25+9=√34 ⇒PQ|=|QR|=|RS|=|SP| ∴ It is a square.