Plane Geometry Calculators
Explore our collection of plane geometry calculators to quickly solve problems involving circles, triangles, polygons, and more. Each calculator comes with formulas and step-by-step solutions for students, teachers, and professionals.
Calculate the area of a ring-shaped figure between two concentric circles.
Area = Ï€ * (Outer Radius^2 – Inner Radius^2)
Compute radius, diameter, circumference, and area of a circle.
- Circumference = 2 * π * Radius
- Area = π * Radius^2
- Diameter = 2 * Radius
Find the distance between two points (x1, y1) and (x2, y2) in 2D space.
Distance = sqrt((x2 – x1)^2 + (y2 – y1)^2)
Calculate area, perimeter, and other properties of common 2D shapes like triangles, rectangles, and polygons.
Varies by shape (e.g., Rectangle: Area = Length * Width, Perimeter = 2 * (Length + Width))
Determine area, perimeter, and angles of a parallelogram.
- Area = Base * Height
- Perimeter = 2 * (Side1 + Side2)
Calculate area, perimeter, and diagonal length of a rectangle.
- Area = Length * Width
- Perimeter = 2 * (Length + Width)
- Diagonal = sqrt(Length^2 + Width^2)
Regular Polygon Calculator (3–14 sides)
Compute area, perimeter, and interior angles for polygons with 3–14 equal sides.
- Perimeter = Number of Sides * Side Length
- Area = (Number of Sides * Side Length^2) / (4 * tan(Ï€ / Number of Sides))
- Interior Angle = ((Number of Sides – 2) * 180) / Number of Sides
Calculate area, side lengths, and diagonals of a rhombus.
- Area = (Diagonal1 * Diagonal2) / 2
- Perimeter = 4 * Side Length
Find the slope of a line passing through two points.
Slope = (y2 – y1) / (x2 – x1)
Calculate area, perimeter, and diagonal of a square.
- Area = Side^2
- Perimeter = 4 * Side
- Diagonal = Side * sqrt(2)
Calculate area and perimeter of a stadium-shaped figure (rectangle with semicircular ends).
- Area = (Length * Width) + (Ï€ * (Width / 2)^2)
- Perimeter = 2 * Length + 2 * π * (Width / 2)
Solve triangles using side lengths and angles.
SideC^2 = SideA^2 + SideB^2 – 2 * SideA * SideB * cos(AngleC)
Solve for unknown sides or angles in any triangle.
SideA / sin(AngleA) = SideB / sin(AngleB) = SideC / sin(AngleC)
Find the midpoint of a line segment between two points.
Midpoint = ((x1 + x2) / 2 , (y1 + y2) / 2)
Pythagorean Theorem Calculator
Solve right triangles for sides or hypotenuse.
Hypotenuse^2 = SideA^2 + SideB^2
Apply fundamental triangle theorems like angle sum and exterior angles.
- Angle Sum: AngleA + AngleB + AngleC = 180
- Exterior Angle: ExteriorAngle = Angle1 + Angle2
Equilateral Triangle Calculator
Calculate all sides, angles, and area of an equilateral triangle.
- Area = (sqrt(3) / 4) * Side^2
- Perimeter = 3 * Side
- Height = (sqrt(3) / 2) * Side
Solve triangles with two equal sides for area, height, and angles.
- Height = sqrt(EqualSide^2 – (Base^2 / 4))
- Area = (Base * Height) / 2
Determine missing sides and angles of right triangles.
- Pythagorean theorem: Hypotenuse^2 = SideA^2 + SideB^2
- sin(Angle) = Opposite / Hypotenuse
- cos(Angle) = Adjacent / Hypotenuse
- tan(Angle) = Opposite / Adjacent
Trigonometry Calculators
Solve angles and sides using sine, cosine, tangent, and their inverses.
- sin(Angle) = Opposite / Hypotenuse
- cos(Angle) = Adjacent / Hypotenuse
- tan(Angle) = Opposite / Adjacent