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Young woman holding a green blank signboard.
Khan Academy
Acute Right and Obtuse Angles, Angles and Intersecting Lines, Geometry
This resource highlights the basics of working with angles and could provide a sound introductory activity for students who are beginning to learn about angles. Eager mathematicians will be introduced to the terminology associated with...
Curated OER
How Do You Find the Sine of an Angle in a Right Triangle?
A trigonometric ratio is a ratio between two sides of a right triangle. In this problem, find sin(A) in the given right triangle. Use the ratio of the opposite side over the hypotenuse.
Curated OER
What are the Legs and Hypotenuse of a Right Triangle?
What are all the parts of a right triangle called? What makes it a right triangle? Legs? Triangles have legs? Hypotenuse? Pythagorean Theorem? The instructor diagrams and identifies all the parts of a right triangle for you.
Curated OER
How Do You Find the Area of a Triangle?
The formula for the area of a triangle is: area equals one half the base times the height. If you have been given these two values then all you need to do is plug them into the formula and solve. Don't forget to write the correct ending...
Curated OER
How Do You Find the Area of a Trapezoid?
Trapezoids can be tricky! Break down the process of finding the area of a trapezoid with an engaging math video. Learners explore area formula and shown exactly how to plug in information, solve, and simplify.
Curated OER
What are Complementary Angles?
Supplementary, obtuse, acute, complementary angles. It's good to know what all of these mean, but let's focus on one at a time. Complementary angles always add up to 90 degrees. So if given one angle in a complementary angle problem, the...
Curated OER
What is a Cone?
What are the things that make a shape a cone? Here's a list of things that define a cone: base, height, vertex, radius, curved side. Are you familiar with all these terms? The teacher diagrams a cone and identifies all the components in...
Curated OER
How Do You Determine if a Triangle Is a Right Triangle if You Know its Sides?
Use the Pythagorean Theorem formula to check if this given triangle, with the given lengths of each side, is a right triangle. It's as simple as plugging the given values into the formula and doing the math to see if the solution checks...
Curated OER
How Do You Solve a Problem Using Indirect Measurement with Shadows?
Using indirect measurement, this video shows viewers how to find the height of a flagpole. The lecturer employs drawings as well as proportions to solve this problem, explaining each step. A useful resource to aid struggling learners and...
Curated OER
How Do You Solve a Problem Using Indirect Measurement with Shadows?
Using indirect measurement, this video shows viewers how to find the height of a flagpole. The lecturer employs drawings as well as proportions to solve this problem, explaining each step. A useful resource to aid struggling learners and...
Curated OER
How Do You Find the Area of a Trapezoid?
Trapezoids can be tricky. Break down the process of finding the area of a trapezoid with this video! Viewers are given information about the area formula and shown exactly how to plug in information, solve, and simplify. This is a...
Virtual Nerd
How Was the Distance Formula Derived?
Are you working on the distance formula? Derive the distance formula and help your learners by showing them the logic behind the distance formula. This practical video should help conceptual understanding and is appropriate for in-class...
Curated OER
How Do You Find the Tangent of an Angle in a Right Triangle?
What's a trigonometric ratio? It is a ratio between two sides of a right triangle. In this problem, find tangent(A) in the given right triangle. Use the ratio of the opposite side divided by the adjacent side to find tan(A). The...
Curated OER
How Do You Find the Volume of a Cone?
The formula to find the volume of a cone is volume equals one-third times the base times the height. The base can be found by using the formula to find the area of a circle: base equals pi times radius squared. So it seems that the area...
Curated OER
How Do You Find the Slant Height of a Cone?
Use the Pythagorean theorem formula to find the slant height of a cone. If the height of the cone and the radius of the base are given, using the Pythagorean theorem formula will be a piece of cake. Just plug in the values given and solve.
Curated OER
How Do You Find the Height of a Triangle if You Know the Area and Base?
Use the formula for the area of a triangle to find the height of the triangle. If the problem gives the value of the area and the value of the base, then the height can be found using the formula for the area of a triangle. The...
Curated OER
How Do You Use Complementary Angles to Find a Missing Angle?
Are complementary angles nice to each other? That's not what complementary means in math. Complementary angles are two angles that add up to 90 degrees and form a right triangle. So if given one value in a problem about complementary...
Curated OER
What is a Rectangle?
What are the characteristics and properties of a quadrilateral that make it a rectangle? Four sides? Right angles? Parallel sides? Watch this video and follow along as the instructor explains the terms and properties that make a...
Curated OER
What is a Parallelogram?
A rectangle, a rhombus, a square, a trapezoid - are any of these a parallelogram? What are the criteria that make a shape a parallelogram? It has something to do with parallel sides, congruent sides, and congruent angles. Help your young...
Curated OER
How Do You Find a Missing Side of a Right Triangle Using Sine?
What's a trigonometric ratio? It is a ratio between two sides of a right triangle. In this problem, find sin(A) in the given right triangle. Use the ratio of the opposite side divided by the hypotenuse to find sin(A). The instructor...
Khan Academy
Khan Academy: Geometry: Measuring Angles in Degrees
Explains how to measure an angle in degrees using a protractor. Defines acute, right, and obtuse angles. Practice problems available. [8:22]