In a triangle, the values of two angles are known. Which triangle is it: acute-angled

In a triangle, the values of two angles are known. Which triangle is it: acute-angled, rectangular or obtuse? a) 65 and 28 degrees b) 54 and 43 degrees

The angles of any triangle add up to 180 °.

Having the sum of two angles, you can calculate the degree measure of the third angle.

To do this, subtract the sum of the two known angles from 180:

a) 180 – (65 + 28) = 180 – 93 = 87 ° third angle.

In this triangle, all angles are less than 90 °, that is, all are sharp.

If all 3 angles in a triangle are acute, then such a triangle is called acute-angled.

b) 180 – (54 + 43) = 180 – 97 = 83 ° third angle.

In this triangle, all 3 corners are also acute, and it is correspondingly acute-angled.