The triangle PQR above is
an obtuse – angled triangle
a scalene triangle
isosceles triangle
an equilateral triangle.
$\begin{align} & P\overset{\wedge }{\mathop{R}}\,Q={{180}^{\text{o}}}-{{128}^{\text{o}}}={{52}^{\text{o}}}\text{ }\!\!\{\!\!\text{ sum of }\angle \text{s on a straight line }\!\!\}\!\!\text{ } \\ & Q\overset{\wedge }{\mathop{P}}\,R+P\overset{\wedge }{\mathop{Q}}\,R+P\overset{\wedge }{\mathop{R}}\,Q={{180}^{\text{o}}}\text{ }\!\!\{\!\!\text{ sum of }\angle \text{s in a }\vartriangle \text{ }\!\!\}\!\!\text{ } \\ & Q\overset{\wedge }{\mathop{P}}\,R+{{76}^{\text{o}}}+{{52}^{\text{o}}}={{180}^{\text{o}}} \\ & Q\overset{\wedge }{\mathop{P}}\,R={{52}^{\text{o}}} \\ & \text{Since two of angles are equal},\text{ the triangle is an isosceles triangle} \\\end{align}$