In triangle ABC, angle A is 9 times greater than angle B, and angle C is less than angle A by 10 degrees.

In triangle ABC, angle A is 9 times greater than angle B, and angle C is less than angle A by 10 degrees. Determine the angles of the triangle and indicate what the triangle is.

We drive the variable x and denote so the degree measure of the smaller of all angles – the angle B. According to the condition of the problem, the angle A will be equal to 9x, and the angle C is equal to (9x – 10 °). All three angles have been determined, we make equations, knowing that the sum of the angles of a triangle is 180 °.
9x + x + (9x – 10 °) = 180 °
19x – 10 ° = 180 °
19x = 190 °
x = 10 ° – angle B.
∠ A = 9 * 10 = 90 °;
∠ С = 90 ° – 10 ° = 80 °.
The degree measure of angle A is 90 ° – a rectangular triangle.
Answer: 90 °, 10 °, 80 ° – the angles of the ABC triangle, respectively, the triangle is rectangular.