TRIANGLES

SPI: 6.4.1Identify, define or describe geometric

shapes given a visual representation or written description of its properties

TRIANGLE

• A triangle is a polygon with three sides and three angles.

The sum of the angles of a triangle is 180° because a triangle is half of a

quadrilateral.

The sum of the measures of the angles of a triangle is 180°.

• Angle 1° + angle 2° + angle 3°=180°

1°

2°

3°

If angle 1=30°, angle 2=100°, what would angle 3 equal?

50°

An acute triangle has all acute angles. (All angles are less than 90 degrees.)

A right triangle is a three sided figure with one right angle.

90°

An obtuse triangle has one obtuse angle (an angle that is more than 90°).

A scalene triangle is a three sided figure that has no angles or sides

equal.

An isosceles triangle has two sides and two angles equal.

An equilateral triangle has equal sides and equal angles.

A plane had wings that are shaped like triangles. Find the missing measure.

40 °X°

50°=x