Triangle Properties and Theorems

What is always true about an equilateral triangle?

• All angles are less than 90°.

• All sides are different lengths.

• All sides and angles are equal.

• It has one 90° angle.

Triangle ABC has angles of 30° and 90°. What's the measure of the third angle?

• 45°

• 30°

• 120°

• 60°

Two angles of a triangle are 30° and 80°. What's the third angle's measure?

• 70°

• 40°

• 60°

• 100°

A triangle has sides of 4 cm, 7 cm, and 10 cm. What is the classification based on its sides?

• Equilateral

• Isosceles

• Right

• Scalene

The longest side of a right triangle is called the:

• Hypotenuse

• Leg

• Base

• Altitude

A right triangle's legs measure 6 ft and 8 ft. What's the hypotenuse length?

• 14 ft

• 10 ft

• 100 ft

• 48 ft

What is the sum of all interior angles in any triangle?

• 360°

• 180°

• 90°

• 270°

Triangles ABC and XYZ have equal corresponding angles. If angle B is 75°, what's angle Y?

• 105°

• 45°

• 150°

• 75°

Which angles are congruent when two lines intersect?

• Supplementary angles

• Vertical angles

• Acute angles

• Obtuse angles

If triangle JKL is isosceles with angle J = 50°, what's angle K's measure?

• 65°

• 50°

• 80°

• 40°