Question

The measures of angles of a triangle are (9x - 5)°, (7x + 5)° and 20x°. Find the value of x. Also, show that the triangle is isosceles.

Answer 1

We know that, sum of the measure of the angles of a triangle is 180°.
9x - 5 + 7x + 5 + 20x = 180°

⇒ 36x = `(180)/(36)`
⇒ x = 5
To show that the triangle is isosceles, we can show that at least teo angles of the triangle are equal.
9x - 5 = 9(5) - 5 = 40
7x + 5 = 7(5) + 5 = 40
So, the triangle is an isosceles triangle.