ANGLES, CIRCLES, ELLIPSES
Angles In Circles Tutorial for calculating angles in circles (central angles, inscribed angles, etc.) formed from radii, chords, tangents and secants.
Central Angle Calculator Calculates a Circle's Central Angle, Radius or Arc Length
Circle Circumference & Area Calculator
CIRCLE Calculator for Radius, Central Angle, Chord, Segment Height, Apothem, Arc Length and Chord Length. If you know two, it will calculate the other five as well as the Sector Area, Segment Area and Circle Area.
ARC to CHORD RATIOS a listing from 1° to 180°
Circle Equation Tutorial
Explains equations of the type x² + y² = r²
Circle Equation Calculator
Input 3 points and it calculates a circle's center radius and equation.
Calculator and tutorial
Types of Triangles
A chart showing triangles classified by angles
(acute, right, obtuse) and by sides (equilateral, isosceles, scalene).
Also has triangle area formulas and a triangle area calculator.
A tutorial discussing the incenter, circumcenter, centroid, orthocenter and the Euler line.
Calculates if 3 sides will form a triangle or not.
Input 3 triangle side lengths and this calculates if the sides will form an equilateral, isosceles, acute, right or obtuse triangle.
Ultimate Triangle Calculator
Input 3 triangle sides, 2 sides with the included angle or 2 angles with the included side and this calculates all the other triangle information.
Side Side Angle Triangle Calculator If you know 2 triangle sides and a non-included angle, this calculates the other side and the other 2 angles.
Right Triangles (Pythagorean Theorem)
30 60 90 and 45 45 90 Triangle Calculator
Quadrilateral page Descriptions and graphics discussing 6 different types of quadrilaterals.
Calculator for Squares and Rectangles
Input side length and either angle and it calculates the area, both diagonals, altitude, perimeter.
Input both diagonals and it calculates the side, area, altitude, perimeter and both angles.
Calculator for Parallelograms
Input two parallelogram sides and one angle and it calculates the area, both diagonals, altitude, perimeter and the angle of intersection of the diagonals.
Input both diagonals and diagonal intersection angle and it calculates area, both sides, altitude, height, perimeter and both angles.
Quadrilateral Kite Calculator
Calculating Trapezoid Area - Tutorial
Regular Polygon Calculator
Input the number of sides and the side length and it calculates the polygon perimeter, all angles (interior, central and exterior), the inradius, the circumradius and the total area.
Calculator for Constructing Regular Polygons
Draw a circle, measure the radius and this calculates the length of the polygon's sides.
Polygons that have integer angles.
A listing of the 22 Regular Polygons whose angles are integers.