# 15 15 25 triangle

### Obtuse isosceles triangle.

Sides: a = 15   b = 15   c = 25

Area: T = 103.6454524699
Perimeter: p = 55
Semiperimeter: s = 27.5

Angle ∠ A = α = 33.55773097619° = 33°33'26″ = 0.58656855435 rad
Angle ∠ B = β = 33.55773097619° = 33°33'26″ = 0.58656855435 rad
Angle ∠ C = γ = 112.8855380476° = 112°53'7″ = 1.97702215667 rad

Height: ha = 13.81992699598
Height: hb = 13.81992699598
Height: hc = 8.29215619759

Median: ma = 19.20328643697
Median: mb = 19.20328643697
Median: mc = 8.29215619759

Inradius: r = 3.76988918072
Circumradius: R = 13.5688010506

Vertex coordinates: A[25; 0] B[0; 0] C[12.5; 8.29215619759]
Centroid: CG[12.5; 2.7643853992]
Coordinates of the circumscribed circle: U[12.5; -5.27664485301]
Coordinates of the inscribed circle: I[12.5; 3.76988918072]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 146.4432690238° = 146°26'34″ = 0.58656855435 rad
∠ B' = β' = 146.4432690238° = 146°26'34″ = 0.58656855435 rad
∠ C' = γ' = 67.11546195238° = 67°6'53″ = 1.97702215667 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.