What is an Isosceles Trapezoid?-Geometry Help

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Video of the Day " Isosceles Triangle"

Today we have three videos that cover properties of an isosceles triangle. An isosceles triangle is a triangle with two congruent angles and sides.

Video one answers the vertex angle sample problems

Video two reviews how to find the base length of an isosceles triangle

Video Three gives directions on how to find the side length of an isosceles triangle

For more on isosceles triangles see:
MooMooMath/Isosceles Triangles

Video of the Day " Finding the Area of an Isosceles Triangle"

Finding the area of a triangle of an isosceles triangle. The formula for area of a triangle is 1/2 base times height.

Step 1. Determine your base
Step 2. Find the altitude
Step 3. You can find the height by creating a right triangle by drawing a line from your vertex.
Step 4. Use the Pythagorean Theorem to determine the missing leg of the right triangle which will be your height.
Step 5. Plug the altitude (height) into 1/2base x height

For more information on area of triangle see
http://www.moomoomath.com/Finding-the-area-of-a-triangle.html#.Ul861VCsiSo

What is so special about a 45-45-90 triangle?

What is so special about a-45-90-45 Triangle?

A 45-45-90 triangle is classified as a special right triangle, but why is it special? Let’s look at the special rules of a 45-45-90 Triangle.

Rule 1. If you know the length of one leg you know the length of the other leg because they are equal.

Rule 2. In order to find the length of the hypotenuse multiply the leg length times the square root of two. This would be written x√2 where x=leg length

Rule 3. In order to find the leg length divide your hypotenuse by the square root of 2.

 

Rule 4 .The area of a 45-45-90 triangle equals 1/2(leg)^2

Let’s look at two examples. 

Example 1 Find the hypotenuse of a 45-45-90 triangle with leg length of 7 units.

 

Step 1. Use x√(2 ) 

Step 2. 7√(2 ) units

Example2. What is the length of one leg of a 45-45-90 triangle if you have a hypotenuse with a length of 12 units?

Step 1. 12/√2  use the formula for leg length hypotenuse divided by square root two

Step 2. 12/√2* √2/√2 

Step 3. (12√2)/2 =6√2