Instructional Video
Khan Academy

Khan Academy: Triangles: Area of Diagonal Triangles of Rectangle Are Equal

9th - 10th
This video shows that the area of diagonal generated triangles of a rectangle are equal.
Instructional Video
Khan Academy

Khan Academy: Triangles: Bhaskara's Proof of Pythagorean Theorem

9th - 10th Standards
An elegant visual proof of the Pythagorean Theorem developed by the 12th century Indian mathematician Bhaskara.
Instructional Video
Khan Academy

Khan Academy: Triangles: Garfield's Proof of the Pythagorean Theorem

9th - 10th
A video explaining how James Garfield's proved the Pythagorean Theorem.
Instructional Video
Khan Academy

Khan Academy: Triangles: Another Pythagorean Theorem Proof

9th - 10th Standards
Students explore the Pythagorean Theorem by exploring a visual proof of the Theorem as they watch a video tutorial.
Instructional Video
Sophia Learning

Sophia: Calculating the Area of a Triangle

9th - 10th Standards
This video lesson demonstrates how to calculate the area of a triangle. It includes detailed examples including ones that use the Pythagorean Theorem. Students can check their understanding with an assessment. [10:43]
Instructional Video
Sophia Learning

Sophia: Calculating the Perimeter of a Triangle

9th - 10th
This video lesson demonstrates how to find the perimeter of triangles. [3:42] The tutorial includes detailed examples. Students can check their understanding with an assessment.
Instructional Video
Sophia Learning

Sophia: Categorizing Triangles With Congruency

9th - 10th
In this video tutorial, triangles are classified as isosceles, equilateral, and scalene by the congruency of their sides. Assess learning with a quiz. [1:52]
Instructional Video
Sophia Learning

Sophia: Classifying Triangles

9th - 10th Standards
This video lesson describes and provides examples of right, acute, and obtuse triangles. Students can check their understanding with an assessment. [2:24]
Instructional Video
Sophia Learning

Sophia: Classifying Triangles by Angle

9th - 10th Standards
This video lesson shows examples of classifying triangles by their angle measurements. Students can check their understanding with an assessment. [3:54]
Instructional Video
Sophia Learning

Sophia: Congruent Triangles

9th - 10th
Congruent triangles are explored in this video lesson. [1:54] The tutorial includes detailed examples and a short assessment.
Instructional Video
Sophia Learning

Sophia: Converse of the Pythagorean Theorem

9th - 10th Standards
Use the Pythagorean theorem to determine if the triangle is a right triangle. Assess learning with a quiz.
Instructional Video
Sophia Learning

Sophia: Introduction to Triangle Similarity

9th - 10th
Similar Triangles are explored in this video lesson. Students can check their understanding with an assessment. [5:51]
Instructional Video
Sophia Learning

Sophia: Isosceles Triangles

9th - 10th
Isosceles triangles are explored in this video tutorial. The lesson models the parts of an isosceles triangle and describes how to find missing angle measures. [5:06]
Instructional Video
Sophia Learning

Sophia: More Difficult Pythagorean Theorem Examples

9th - 10th
Solve the Pythagorean theorem that contains radicals and assess learning with a quiz.
Instructional Video
Sophia Learning

Sophia: Pythagorean Theorem and Right Triangles

9th - 10th Standards
Determine if the Pythagorean theorem can be used with triangles that are not right triangles. Assess learning with a quiz.
Instructional Video
Sophia Learning

Sophia: Pythagorean Theorem Proof

9th - 10th Standards
Prove the Pythagorean theorem and take a quiz to assess learning.
Instructional Video
Sophia Learning

Sophia: Quadrilaterals and Triangles

9th - 10th
In this video tutorial [4:17], students will explore the attributes that triangles and quadrilaterals have and how they share certain properties. Assess learning with a quiz.
Instructional Video
Sophia Learning

Sophia: Quadrilaterals and Triangles

9th - 10th
This video lesson [4:55] describes the characteristics that quadrilaterals and triangles have in common. Students can check their understanding with an assessment.
Instructional Video
Sophia Learning

Sophia: Scalene, Isosceles, and Equilateral Triangles

9th - 10th
This video lesson [2:10] shows examples for classifying triangles by their side lengths. Students can check their understanding with an assessment.
Instructional Video
Sophia Learning

Sophia: Special Right Triangles

9th - 10th Standards
Special right triangles are investigated in this video tutorial. The lesson provides background knowledge and two videos that show the relationships of the sides in special right triangles and practice problems to test students'...
Instructional Video
Sophia Learning

Sophia: Triangle Congruence Theorem (Hl)

9th - 10th
This video lesson introduces and provides examples of the Hypotenuse-Leg Triangle Congruence Theorem. Students can check their understanding with an assessment.
Instructional Video
Sophia Learning

Sophia: Triangle Height

9th - 10th
In this video tutorial, explore how to determine the height of obtuse, acute, and right triangles. Take a quiz to assess learning. [6:15]
Instructional Video
Sophia Learning

Sophia: Triangle Interior Angles Practice

9th - 10th
Determine the value of a variable when solving for the interior angles of a triangle. Check understanding with a quiz.
Instructional Video
Sophia Learning

Sophia: Angles of a Triangle

9th - 10th
This video tutorial demonstrates how to find the interior and exterior angles of a triangle.