An exterior angle of a triangle measures 125° and one of the remote interior angles measures 35°. The triangle must be

acute

obtuse

right

The exterior angle of one is 125°. exterior angle is when one of the sides of a triangle is extended and the adjacent angle of that interior angle of the triangle.

the interior angle + exterior angle together make a straight line.

central angle of a straight line is 180°.

interior angle + 125° = 180°

interior angle = 55°

one of the other angles is 35°

the sum of the interior angles of a triangle is 180°

we already know magnitudes of 2 angles, they are 55° and 35°

the third angle - X is

55° + 35° + X = 180°

X + 90° = 180°

X = 90°

the third angle is a right angle.

triangles with 1 right angle is called a right angled triangle

triangles with 1 obtuse angle is called an obtuse angled triangle

triangles with all three angles being acute angles is called an acute angled triangle

in this instance one of the angles is a right angle

therefore its a right angle triangle