More Lessons for Grade 8

Math Worksheets

Videos, worksheets, stories, and solutions to help Grade 8 students learn about the special right triangles: 45-45-90, 30-60-90.

How to find missing sides and angles in special right triangles?

Special Right Triangles: 30-60-90 and 45-45-90 Triangles

Students learn that in a 45-45-90 triangle, the legs are congruent, and the length of the hypotenuse is equal to root 2 times the length of a leg. Students also learn that in a 30-60-90 triangle, the length of the long leg is equal to root 3 times the length of the short leg, and the length of the hypotenuse is equal to 2 times the length of the short leg.

This video discusses two special right triangles, how to derive the formulas to find the lengths of the sides of the triangles by knowing the length of one side, and then do a few examples using them!

If you are given one side of a 45-45-90 triangle or one side of a 30-60-90 triangle you have enough information to solve for each of the two missing sides.

This video shows how to do it going from smaller sides to larger sides and larger sides to smaller sides. It also shows how the found sides can be used to find the perimeter and area of the right triangle.

Explaining How to find the missing sides of right triangles using the relationships of sides for 30-60-90 right triangles, 45-45-90 right triangles, and 3-4-5 right triangles

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