3. Triangles

3.01 Triangles and angles

3.02 Isosceles and equilateral triangles

3.03 Triangle inequalities

3.04 Angle and perpendicular bisectors

3.05 Medians and altitudes

3.06 Midsegments

United States of America

Grades 9-12

3.01 Triangles and angles

Adaptive

Worksheet

Interactive practice questions

What is the sum of the measures of the interior angles of any triangle?

The measures add to $\editable{}$ °

Easy

< 1min

A triangle has two angles measuring $72^\circ$72° and $58^\circ$58°. Determine the measure of the third angle.

Easy

< 1min

Consider the diagram below.

Easy

< 1min

Consider the diagram below.

Medium

< 1min

Outcomes

G.CO.C.10

Prove theorems about triangles. Theorems include: measures of interior angles of a triangle sum to 180°; base angles of isosceles triangles are congruent; the segment joining midpoints of two sides of a triangle is parallel to the third side and half the length; the medians of a triangle meet at a point.

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