Geometry proofs

Some of the most important geometry proofs are demonstrated here. I will provide you with solid and thorough examples.




Observations, measurements, and experimentations are not proof

If a formula works for 1 million specific examples, this is still not a proof

Understanding a proof can be a daunting task. Writing a proof can even be more daunting

I kept the reader(s) in mind when I wrote the proofs outlines below.

My approach is to explain everything at the same time I am writing the proof

If you are interested in proofs, you will find the proofs below a pleasure to read


Area of shapes proofs



Proof of the area of a circle
Here, we prove that the area of a circle is pi × r2 by inscribing circles into polygons

Proof of the area of a triangle
A crystal clear proof of the area of a triangle. We will know why it makes sense to multiply the base by the height and divide the result by two.

Proof of the area of a parallelogram
Here, we prove that the area of a parallelogram is base times height by turning a parallelogram into a rectangle.

Proof of the area of a trapezoid
Here, we prove that the area of a trapezoid is the average of the two parallel bases times the height by turning a trapezoid into a rectangle.


Proofs related to triangles



Proof of the angle sum theorem
A crystal clear proof of the angle sum theorem.

Triangle inequality theorem proof
A crystal clear proof of the triangle inequality theorem.

Base angles theorem proof
A crystal clear proof of the base angles theorem.

Right isosceles triangle
Prove that the median of a right isosceles triangle is half the hypotenuse




Proofs related to angles



Vertical angles theorem proof
See a proof of the vertical angles theorem.

Proofs related to quadrilaterals



Prove that opposite sides of a parallelogram are congruent
See how to prove that opposite sides of a parallelogram are equal.

Prove that the diagonals of a rectangle are congruent
See how to prove that the diagonals of a rectangle are equal.

Prove that the diagonals of a trapezoid are congruent
See how to prove that the diagonals of a trapezoid are equal.




Buy a comprehensive geometric formulas ebook. All geometric formulas are explained with well selected word problems.





Recent Articles

  1. Linear Parent Function

    Nov 20, 17 11:18 AM

    What is a linear parent function? Crystal clear explanation.

    Read More

New math lessons

Your email is safe with us. We will only use it to inform you about new math lessons.

            Follow me on Pinterest





Recent Lessons

  1. Linear Parent Function

    Nov 20, 17 11:18 AM

    What is a linear parent function? Crystal clear explanation.

    Read More

  Our Top Pages

Formula for percentage

Compatible numbers

Basic math test

Basic math formulas

Types of angles

Math problem solver

Algebra word problems

Surface area of a cube

Finding the average 

Scale drawings

Tough Algebra Word Problems.

If you can solve these problems with no help, you must be a genius!


Everything you need to prepare for an important exam!

K-12 tests, GED math test, basic math tests, geometry tests, algebra tests. 


Real Life Math Skills

Learn about investing money, budgeting your money, paying taxes, mortgage loans, and even the math involved in playing baseball.

 Recommended

Scientific Notation Quiz

Types of Angles Quiz

Graphing Slope Quiz

Adding and Subtracting Matrices Quiz  

Factoring Trinomials Quiz 

Solving Absolute Value Equations Quiz  

Order of Operations Quiz