# 7 7 13 triangle

### Obtuse isosceles triangle.

Sides: a = 7   b = 7   c = 13

Area: T = 16.88774953738
Perimeter: p = 27
Semiperimeter: s = 13.5

Angle ∠ A = α = 21.78767892983° = 21°47'12″ = 0.38802512067 rad
Angle ∠ B = β = 21.78767892983° = 21°47'12″ = 0.38802512067 rad
Angle ∠ C = γ = 136.4266421403° = 136°25'35″ = 2.38110902402 rad

Height: ha = 4.82549986782
Height: hb = 4.82549986782
Height: hc = 2.59880762114

Median: ma = 9.83661577865
Median: mb = 9.83661577865
Median: mc = 2.59880762114

Inradius: r = 1.25109255832
Circumradius: R = 9.43300543968

Vertex coordinates: A[13; 0] B[0; 0] C[6.5; 2.59880762114]
Centroid: CG[6.5; 0.86660254038]
Coordinates of the circumscribed circle: U[6.5; -6.83219781854]
Coordinates of the inscribed circle: I[6.5; 1.25109255832]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 158.2133210702° = 158°12'48″ = 0.38802512067 rad
∠ B' = β' = 158.2133210702° = 158°12'48″ = 0.38802512067 rad
∠ C' = γ' = 43.57435785965° = 43°34'25″ = 2.38110902402 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 ### 6. Inradius ### 7. Circumradius ### 8. Calculation of medians #### Look also our friend's collection of math examples and problems:

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