Distance between A Point and A line

Before you see this post,

see

A Property of Perpendicular Lines

correction in picture : parpendicular -> perpendicular

A Property of Perpendicular Lines

Radian

Graph of Trigonometric Function : Sine, Cosine and Tangent

Before you see this post,

see

Trigonometric Function : Sine, Cosine and Tangent

Trigonometric Function : Sine, Cosine and Tangent

               In Right-angled triangle, they are defined like the picture below.

sine -> sin

cosine -> cos

tangent -> tan

In Cartesian coordinate system, 

we can notate trigonometric functions, sine, cosine and tangent, 

like the picture above.

Sum of Angles of An n-polygon

Before you see this post,

see

Sum of Angles of Quadrangle, Pentagon, Hexagon

Let's make an n-polygon.

To make a figure that is an angle more than a former one.

put a triangle to a former one.

we can make an n-polygon by process like the picture above.

Sum of Angles of Quadrangle, Pentagon, Hexagon

Before you see this post,

see

Proof of Sum of Angles of A Triangle

5 Postulates of Euclidean Geometry

1. "To draw a straight line from any point to any point."

2. To produce [extend] a finite straight line continuously in a straight line."

3. "To describe a circle with any centre and distance [radius]."

4. "That all right angles are equal to one another."

( right angle = 90˚ )

5. The parallel postulate: 

"That, if a straight line falling on two straight lines make the interior angles on the same side less than two right angles, the two straight lines, 

if produced indefinitely, meet on that side on which are the angles less than the two right angles."

If you want to know more about Euclidean Geometry,

click

Here

or search Euclidean Geometry on SEARCH TAP.

Various Proofs of Pythagorean Theorem

There are various proofs of Pythagorean Theorem.

I will show you 3 proofs.

There would be more proofs.

Do you want to see more proofs,

click

Pythagorean theorem

and reply more proofs.