Triangle calculator SAS

Please enter two sides of the triangle and the included angle
°


Right isosceles triangle.

Sides: a = 2.5   b = 2.5   c = 3.53655339059

Area: T = 3.125
Perimeter: p = 8.53655339059
Semiperimeter: s = 4.2687766953

Angle ∠ A = α = 45° = 0.78553981634 rad
Angle ∠ B = β = 45° = 0.78553981634 rad
Angle ∠ C = γ = 90° = 1.57107963268 rad

Height: ha = 2.5
Height: hb = 2.5
Height: hc = 1.7687766953

Median: ma = 2.79550849719
Median: mb = 2.79550849719
Median: mc = 1.7687766953

Inradius: r = 0.7322233047
Circumradius: R = 1.7687766953

Vertex coordinates: A[3.53655339059; 0] B[0; 0] C[1.7687766953; 1.7687766953]
Centroid: CG[1.7687766953; 0.5899255651]
Coordinates of the circumscribed circle: U[1.7687766953; -0]
Coordinates of the inscribed circle: I[1.7687766953; 0.7322233047]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 135° = 0.78553981634 rad
∠ B' = β' = 135° = 0.78553981634 rad
∠ C' = γ' = 90° = 1.57107963268 rad

Calculate another triangle




How did we calculate this triangle?

1. Calculation of the third side c of the triangle using a Law of Cosines

a = 2.5 ; ; b = 2.5 ; ; gamma = 90° ; ; ; ; c**2 = a**2+b**2 - 2ab cos( gamma ) ; ; c = sqrt{ a**2+b**2 - 2ab cos( gamma ) } ; ; c = sqrt{ 2.5**2+2.5**2 - 2 * 2.5 * 2.5 * cos(90° ) } ; ; c = 3.54 ; ;


Now we know the lengths of all three sides of the triangle and the triangle is uniquely determined. Next we calculate another its characteristics - same procedure as calculation of the triangle from the known three sides SSS.

a = 2.5 ; ; b = 2.5 ; ; c = 3.54 ; ;

2. The triangle circumference is the sum of the lengths of its three sides

p = a+b+c = 2.5+2.5+3.54 = 8.54 ; ;

3. Semiperimeter of the triangle

s = fraction{ o }{ 2 } = fraction{ 8.54 }{ 2 } = 4.27 ; ;

4. The triangle area using Heron's formula

T = sqrt{ s(s-a)(s-b)(s-c) } ; ; T = sqrt{ 4.27 * (4.27-2.5)(4.27-2.5)(4.27-3.54) } ; ; T = sqrt{ 9.77 } = 3.13 ; ;

5. Calculate the heights of the triangle from its area.

T = fraction{ a h _a }{ 2 } ; ; h _a = fraction{ 2 T }{ a } = fraction{ 2 * 3.13 }{ 2.5 } = 2.5 ; ; h _b = fraction{ 2 T }{ b } = fraction{ 2 * 3.13 }{ 2.5 } = 2.5 ; ; h _c = fraction{ 2 T }{ c } = fraction{ 2 * 3.13 }{ 3.54 } = 1.77 ; ;

6. Calculation of the inner angles of the triangle using a Law of Cosines

a**2 = b**2+c**2 - 2bc cos( alpha ) ; ; alpha = arccos( fraction{ a**2-b**2-c**2 }{ 2bc } ) = arccos( fraction{ 2.5**2-2.5**2-3.54**2 }{ 2 * 2.5 * 3.54 } ) = 45° ; ; beta = arccos( fraction{ b**2-a**2-c**2 }{ 2ac } ) = arccos( fraction{ 2.5**2-2.5**2-3.54**2 }{ 2 * 2.5 * 3.54 } ) = 45° ; ; gamma = arccos( fraction{ c**2-a**2-b**2 }{ 2ba } ) = arccos( fraction{ 3.54**2-2.5**2-2.5**2 }{ 2 * 2.5 * 2.5 } ) = 90° ; ;

7. Inradius

T = rs ; ; r = fraction{ T }{ s } = fraction{ 3.13 }{ 4.27 } = 0.73 ; ;

8. Circumradius

R = fraction{ a }{ 2 * sin( alpha ) } = fraction{ 2.5 }{ 2 * sin 45° } = 1.77 ; ;




Look also our friend's collection of math examples and problems:

See more informations about triangles or more information about solving triangles.