Question

The angles of a triangle are in the ratio 3: 4: 5. The triangle is:

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

Answer 1

The correct option is C an acute angled triangle

Let the proportional quantity be x
so, $3x+4x+5x={180}^{\circ }$
$12x={180}^{\circ }$
$x={15}^{\circ }$
So, angle of triangles are:
${15}^{\circ }\times 3={45}^{\circ }$
${15}^{\circ }\times 4={60}^{\circ }$
${15}^{\circ }\times 5={75}^{\circ }$
Since, all the angles are less than ${90}^{\circ }$, the given triangle is an acute angled triangle.