Question

1. name the triangle with the following characteristics. sides: 5 cm, 5 cm, 6.4 cm; angles: 80° and 50°. acute isosceles triangle obtuse scalene triangle equiangular equilateral triangle right isosceles triangle

Explanation:

Step1: Determine the type of triangle by sides

Since two sides are equal ($5$ cm and $5$ cm), it is an isosceles triangle.

Step2: Determine the third angle

Using the angle - sum property of a triangle ($\angle A+\angle B+\angle C = 180^{\circ}$). Let the third angle be $x$. Then $80^{\circ}+50^{\circ}+x=180^{\circ}$. So, $x = 180^{\circ}-(80^{\circ}+50^{\circ})=50^{\circ}$.

Step3: Determine the type of triangle by angles

All angles ($80^{\circ},50^{\circ},50^{\circ}$) are less than $90^{\circ}$. So, it is an acute triangle.

Answer:

acute isosceles triangle