# Triangles

by
**kfrankl**

Last updated 5 years ago

** Discipline: **

Math ** Subject: **

Geometry
** Grade:**

3,4

ANGLES

ACUTE: measure is less than 90 degrees

RIGHT: measure equals 90 degrees

OBTUSE: measure is greater than 90 degrees

DEFINITION

A triangle is a three-sided figure with straight edges whose angles add up to 180 degrees.

TYPES

SCALENE: all angles and sides have different measures

EQUILATERAL: all sides are congruent and all angles equal 60 degrees

ISOSCELES: has two equal sides, and the angles opposite of these sides are equal as well

TRIANGLES

TERMS TO KNOW:congruent: equal in size

Youtube video proving the Pythagorean Theorm, which says a^2+b^2=c^2 where a and b are the two shortest sides of a right triangle and c is the longest side of a right triangle.

Triangle Game

CITATIONS:[Right angle, obtuse angle, ' acute angle picture] Mathblaster.com. Retrieved on 2/22/15 from http://www.mathblaster.com/coolmath/articles/angles.[Scalene triangle picture] Learnalberta.ca. Retrieved on 2/22/15 from http://www.learnalberta.ca/content/memg/Division03/Scalene%20Triangle/index.html.[Equilateral triangle picture] Brilliant.org. Retrieved on 2/22/15 from https://brilliant.org/wiki/properties-of-equilateral-triangles/.[Isosceles triangle picture] Wyzant.com. Retrieved on 2/22/15 from http://www.wyzant.com/resources/lessons/math/geometry/triangles/isosceles_and_equilateral_triangles[Youtube video] Youtube.com. Retrieved on 2/22/15 from https://www.youtube.com/watch?v=CAkMUdeB06o.

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