Curated OER
What is the Formula for the Area of a Triangle?
The teacher explains how the formula for a triangle was determined. It is related to a parallelogram. What? The formula for the area of a triangle is derived from the area of a parallelogram? Seeing is believing, so watch this video to...
Curated OER
How Do You Solve a Word Problem by Dividing Monomials?
A word problem, a triangle, monomials, exponents, what to do? The instructor explains how to set up this ratio in order to solve the problem and express it as a monomial in simplest form.
Corbett Maths
Angles in a Triangle
The third angle's the charm. Viewers of a short video learn how to find the measure of the missing angle in a triangle. It uses an arithmetic process rather than an algebraic one, so younger learners have no trouble understanding the...
Socratica
Sum of the Angles in a Triangle
You know that triangles have angle sums of 180 degrees, but can you prove it? A brief video in the Socratica Geometry series highlights an informal geometric proof. It shows that the sum of the interior angles of a triangle is 180...
Curated OER
How Do You Find a Missing Side of a Right Triangle Using Tangent?
Identify the variables, identify the given values and use a formula to find the missing length in this right triangle problem. What formula? The tangent ratio, which is normally used to show a ratio between two sides of a right triangle,...
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 Cosine 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 cosine(A) in the given right triangle. Use the ratio of the adjacent side divided by the hypotenuse to find cos(A). The instructor...
Curated OER
How Do You Find the Lateral and Surface Areas of a Triangular Prism?
There are several pieces to this problem. But luckily all the necessary pieces are here. There are five variables and three different formulas to use to get the solutions. The instructor diagrams the triangular prism and labels the...
Curated OER
What is the Formula for the Area of a Triangle?
The teacher explains how the formula for a triangle was determined. It is related to a parallelogram. What? The formula for the area of a triangle is derived from the area of a parallelogram? Seeing is believing, so watch this video to...
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 Classify Triangles?
Triangles are classified by their angle measurement as well as by the length of their sides. Here are some names that identify the types of triangles: isosceles, equilateral, scalene, obtuse, and acute. Watch this video to learn about...
Curated OER
What are Equilateral, Isosceles, and Scalene Triangles?
Triangles are classified by their angle measurement as well as by the length of their sides. Here are some names that identify the types of triangles: right, isosceles, equilateral, scalene, obtuse, and acute. Watch this video to learn...
Curated OER
What are Acute, Obtuse, and Right Triangles?
Triangles are classified by their angle measurement as well as by the length of their sides. Here are some names that identify the types of triangles: right, isosceles, equilateral, scalene, obtuse, and acute. Watch this video to learn...
Curated OER
How Do You Find the Angles in a Triangle if You Have a Ratio of Their Measures?
Use the Triangle Sum Theorem to find the value of each of the inside angles of a triangle. This triangle problem has to do with the ratio of the angles to each other. Find the measure of each angle if the ratio is 1:3:8. Not sure how to...
Curated OER
How Do You Find a Missing Angle in a Right Triangle?
The triangle sum theorem states that the interior angles of a triangle add up to 180 degrees. So it seems logical that if there are two known values given for the interior angles of a triangle, the third value could be found using this...
Curated OER
How Do You Find Missing Angles in an Isosceles Triangle Using Right Triangles?
Given an isosceles triangle, and the value of one angle, find the missing values. There are some special properties about isosceles triangles. Use the triangle sum theorem to solve this problem. Watch this video to see how the instructor...
Curated OER
What is a Polygon?
What makes a figure a polygon? Does it have three or more sides? Is it a closed figure? If the answer is yes to both of those questions then it's a polygon. But wait! Some of these polygons have special names based on the number of sides...
Curated OER
How Do You Find the Sum of the Interior Angles of a Polygon?
Squares, pentagons, triangles, polygons. How is it possible to figure out the sum of the interior angles of any of these multi-faceted shapes? There's got to be a formula. Of course there's a formula. That's what algebra is all about,...
Curated OER
What Does Congruent Mean?
Two figures are congruent if they have the same size and shape. Line segments can also be congruent if they are of the same length. Vertical angles created by intersecting lines are always congruent. Polygons that have matching angles...
Curated OER
What is a Pyramid?
One base, triangular sides, and defined polygons are all parts of what make up a pyramid. Check out this video and see the instructor draw pictures of a variety of pyramids. She identifies the specific parts and gives them names based on...
Curated OER
How Do You Find Missing Angles in an Isosceles Triangle?
Finding the missing values of two angles in an isosceles triangle is not as difficult as it sounds. But how can two out of three angle's measurements be found? Well, there are special properties about an isosceles triangle which make...
Curated OER
How Do You Find a Missing Angle in a Triangle?
The interior angles of any and ALL triangles adds up to 180 degrees. So if given two of the angle degrees, is it possible to find the value of the third angle? Yes! Use the triangle sum theorem to solve for the missing angle. Watch this...
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...
Curated OER
How Do You Find the Length of a Leg of a Right Triangle?
A right triangle. Two given measurements for two side lengths and one unknown length. Use the Pythagorean theorem to solve this problem and find the missing value. Squares and square roots are used in this problem and don't worry when...