The vertices of the given triangle are A (4,4), B(3,5), and C(–1,–1)It is known that the slope (m) of a non-vertical line passing through the points (x1​,y1​) and (x2​,y2​) is given by m=x2​−x1​y2​−y1​​,x2​=x1​ ∴ Slope of AB(m1​)=3−45−4​≡−1 Slope of BC(m2​)=−1−3−1−5​=−4−6​=23​ Slope of CA(m3​)=4+14+1​=55​=1 It is observed that m1​m3​=−1 This shows that line segments AB and CA are perpendicular to each otheri.e., the given triangle is right-angled at A(4,4).Thus, the points (4,4),(3,5), and (−1,−1) are the vertices of a right-angled triangle.