# 7 7 12 triangle

### Obtuse isosceles triangle.

Sides: a = 7   b = 7   c = 12

Area: T = 21.63333076528
Perimeter: p = 26
Semiperimeter: s = 13

Angle ∠ A = α = 31.00327191339° = 31°10″ = 0.5411099526 rad
Angle ∠ B = β = 31.00327191339° = 31°10″ = 0.5411099526 rad
Angle ∠ C = γ = 117.9954561732° = 117°59'40″ = 2.05993936017 rad

Height: ha = 6.18109450437
Height: hb = 6.18109450437
Height: hc = 3.60655512755

Median: ma = 9.17987798753
Median: mb = 9.17987798753
Median: mc = 3.60655512755

Inradius: r = 1.66441005887
Circumradius: R = 6.79550774038

Vertex coordinates: A[12; 0] B[0; 0] C[6; 3.60655512755]
Centroid: CG[6; 1.20218504252]
Coordinates of the circumscribed circle: U[6; -3.19895261283]
Coordinates of the inscribed circle: I[6; 1.66441005887]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 148.9977280866° = 148°59'50″ = 0.5411099526 rad
∠ B' = β' = 148.9977280866° = 148°59'50″ = 0.5411099526 rad
∠ C' = γ' = 62.00554382677° = 62°20″ = 2.05993936017 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.