# 4 12 12 triangle

### Acute isosceles triangle.

Sides: a = 4   b = 12   c = 12

Area: T = 23.66443191324
Perimeter: p = 28
Semiperimeter: s = 14

Angle ∠ A = α = 19.18881364537° = 19°11'17″ = 0.33548961584 rad
Angle ∠ B = β = 80.40659317731° = 80°24'21″ = 1.40333482476 rad
Angle ∠ C = γ = 80.40659317731° = 80°24'21″ = 1.40333482476 rad

Height: ha = 11.83221595662
Height: hb = 3.94440531887
Height: hc = 3.94440531887

Median: ma = 11.83221595662
Median: mb = 6.63332495807
Median: mc = 6.63332495807

Inradius: r = 1.69903085095
Circumradius: R = 6.0855110634

Vertex coordinates: A[12; 0] B[0; 0] C[0.66766666667; 3.94440531887]
Centroid: CG[4.22222222222; 1.31546843962]
Coordinates of the circumscribed circle: U[6; 1.01441851057]
Coordinates of the inscribed circle: I[2; 1.69903085095]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 160.8121863546° = 160°48'43″ = 0.33548961584 rad
∠ B' = β' = 99.59440682269° = 99°35'39″ = 1.40333482476 rad
∠ C' = γ' = 99.59440682269° = 99°35'39″ = 1.40333482476 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.