# Triangle Calculator Online

## Find Missing Angles and Sides of A Triangle. Solve SSS, SAS, SSA using the Triangle Calculator.

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Triangle Calculator

You can input in any of the fields and get equivalent values.

Area : sq cm

Perimeter : cm

## Rules for Triangle

These are some of the basic rules of a triangle:

• ### Triangle Sum Property:

The sum of the three interior angles of a triangle is always equal to 180 degrees.
• ### Triangle Inequality Theorem:

The sum of the length of any two sides of a triangle is always greater than the length of the third side.
• ### Exterior Angle Property:

An exterior angle of a triangle is equal to the sum of its two interior opposite angles.
• ### Congruent Triangles:

Two triangles are said to be congruent if the lengths of the corresponding sides of the triangle are equal.
• ### Similar Triangles:

Two triangles are said to be similar if the lengths of the corresponding sides of the triangle are equal.
• ### Pythagorean Theorem

In a right-angled triangle (a triangle with one 90-degree angle),the square of the length of the hypotenuse(the side opposite the right angle) is equal to the sum of the squares of the lengths of the other two sides.

• ### Triangle Centers

Triangles have several important points called centers. These include the centroid (the point of intersection of the medians),the circumcenter (the center of the circle passing through the three vertices),theincenter (the center of the circle inscribed inside the triangle), and theorthocenter (the point of intersection of the altitudes).