12 13 13 triangle

Acute isosceles triangle.

Sides: a = 12   b = 13   c = 13

Area: T = 69.1955375568
Perimeter: p = 38
Semiperimeter: s = 19

Angle ∠ A = α = 54.97328525008° = 54°58'22″ = 0.95994572754 rad
Angle ∠ B = β = 62.51435737496° = 62°30'49″ = 1.09110676891 rad
Angle ∠ C = γ = 62.51435737496° = 62°30'49″ = 1.09110676891 rad

Height: ha = 11.53325625947
Height: hb = 10.64554423951
Height: hc = 10.64554423951

Median: ma = 11.53325625947
Median: mb = 10.68987791632
Median: mc = 10.68987791632

Vertex coordinates: A[13; 0] B[0; 0] C[5.53884615385; 10.64554423951]
Centroid: CG[6.17994871795; 3.54884807984]
Coordinates of the circumscribed circle: U[6.5; 3.38217288811]
Coordinates of the inscribed circle: I[6; 3.6421861872]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 125.0277147499° = 125°1'38″ = 0.95994572754 rad
∠ B' = β' = 117.486642625° = 117°29'11″ = 1.09110676891 rad
∠ C' = γ' = 117.486642625° = 117°29'11″ = 1.09110676891 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    