# 14 14 21 triangle

### Obtuse isosceles triangle.

Sides: a = 14   b = 14   c = 21

Area: T = 97.23113606816
Perimeter: p = 49
Semiperimeter: s = 24.5

Angle ∠ A = α = 41.41096221093° = 41°24'35″ = 0.72327342478 rad
Angle ∠ B = β = 41.41096221093° = 41°24'35″ = 0.72327342478 rad
Angle ∠ C = γ = 97.18107557815° = 97°10'51″ = 1.6966124158 rad

Height: ha = 13.89901943831
Height: hb = 13.89901943831
Height: hc = 9.26601295887

Median: ma = 16.41664551594
Median: mb = 16.41664551594
Median: mc = 9.26601295887

Inradius: r = 3.96986269666
Circumradius: R = 10.58330052443

Vertex coordinates: A[21; 0] B[0; 0] C[10.5; 9.26601295887]
Centroid: CG[10.5; 3.08767098629]
Coordinates of the circumscribed circle: U[10.5; -1.32328756555]
Coordinates of the inscribed circle: I[10.5; 3.96986269666]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 138.5990377891° = 138°35'25″ = 0.72327342478 rad
∠ B' = β' = 138.5990377891° = 138°35'25″ = 0.72327342478 rad
∠ C' = γ' = 82.81992442185° = 82°49'9″ = 1.6966124158 rad

# How did we calculate this triangle?

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. ### 1. The triangle circumference is the sum of the lengths of its three sides ### 2. Semiperimeter of the triangle ### 3. The triangle area using Heron's formula ### 4. Calculate the heights of the triangle from its area. ### 5. Calculation of the inner angles of the triangle using a Law of Cosines    