Question

If the angles of a triangle are in the ratio $1:2:7,$ then the triangle is:

• A. an acute angled triangle
• B. an obtuse angled triangle
• C. a right angled triangle
• D. a right angled isosceles triangle

Answer 1

The correct option is B an obtuse angled triangle

Let the angles be $1x,2x,7x.$
We have
$1x+2x+7x={180}^{\circ }$
$x={18}^{\circ }$
The angles are ${18}^{\circ }$, ${36}^{\circ }$ and ${126}^{\circ }$.
$\therefore$ The $\Delta$ is an obtuse angled triangle.