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Geometry area formulas of a circle, sphere, triangle, rectangular, parallelogram, rhombus, ellipse, trapezoid, cone, surface area of a cone, cylinder, surface area of a cylinder, any circular sector and a general formula for any polygon with SolveMyMath.com Area Formulas!
Shape  Formula  Variables 

Area of a Rectangle 
l and w are the length and width of the triangle. 

Area of a Parallelogram (in general) 
b and h are the length of the base and of the perpendicular height  
Area of a Rhombus 
a and b are the lengths of the two diagonals of the rhombus. 

Area of a Triangle 
b and h are the base and altitude (height), respectively. 

Area of a Circle 
r is the radius. 

Area of a Ellipse 
a and b are the semimajor and semiminor axis. 

Area of a Sphere, Circular area 
, or  r is the radius and d the diameter. 
Area of a Trapezoid 
a and b are the parallel sides and h the distance (height) between the parallels. 

Any Regular Polygon Area 
a is the apothem, or the radius of an inscribed circle in the polygon, and p is the perimeter of the polygon.  
Area of a Cylinder 
r and h are the radius and height, respectively. 

Lateral surface area of a cylinder  r and h are the radius and height, respectively. 

Area of a Cone 
r and l are the radius and slant height, respectively. 

Lateral surface area of a cone 
r and l are the radius and slant height, respectively. 

Area of a Circular sector 
r and θ are the radius and angle (in radians), respectively. 