# 9 9 15 triangle

### Obtuse isosceles triangle.

Sides: a = 9   b = 9   c = 15

Area: T = 37.31220288915
Perimeter: p = 33
Semiperimeter: s = 16.5

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 = 8.29215619759
Height: hb = 8.29215619759
Height: hc = 4.97549371855

Median: ma = 11.52217186218
Median: mb = 11.52217186218
Median: mc = 4.97549371855

Inradius: r = 2.26113350843
Circumradius: R = 8.14108063036

Vertex coordinates: A[15; 0] B[0; 0] C[7.5; 4.97549371855]
Centroid: CG[7.5; 1.65883123952]
Coordinates of the circumscribed circle: U[7.5; -3.16658691181]
Coordinates of the inscribed circle: I[7.5; 2.26113350843]

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.