It depends on what information you have. If you have only the lengths of the three sides, you would need to use the cosine rule.
An interior angle is any angle on the interior of the triangle.
A triangle with a 90o interior angle is called a 'right' triangle. BTW, any triangle can have only one 90o interior angle
interior is the inside of a triangle but is connected to the triangle.
You cannot.
A heptagon. It can have a reflex interior angle, a triangle cannot.
They are all 60 degrees.
The Exterior Angle Theorem states that the measure of an exterior angle of a triangle is equal to the sum of the measures of the two non-adjacent interior angles. To find the exterior angle, extend one side of the triangle and measure the angle formed outside the triangle. You can then calculate this angle by adding the measures of the two opposite interior angles. This theorem is useful in solving problems involving triangle geometry and angle relationships.
To find the exterior angle of a triangle, first identify the two adjacent interior angles that form the exterior angle. The measure of the exterior angle is equal to the sum of these two interior angles. Alternatively, you can use the property that each exterior angle is equal to 180 degrees minus the adjacent interior angle. This relationship holds for all triangles.
To find the measure of an exterior angle of a triangle, you can use the property that the exterior angle is equal to the sum of the two opposite interior angles. First, identify the exterior angle you want to measure, and then add the measures of the two non-adjacent interior angles. Alternatively, if you know the measure of one interior angle, you can subtract it from 180 degrees to find the exterior angle at that vertex.
Either could have a larger interior angle. If they were regular, then the interior angle of a triangle would be 60 degrees whereas that of a heptagon would be 128.57 degrees. The REGULAR heptagon would have a larger interior angle than a REGULAR triangle.
measure of exterior angle of triangle is equal to sum of interior angles. for eg. In triangle ABC, angle C is exterior angle angle A and angle B are interior angles so, C=A+B
Add the first two angles together and subtract the total from 180 to find the 3rd angle