# 5 9 9 triangle

### Acute isosceles triangle.

Sides: a = 5   b = 9   c = 9

Area: T = 21.61545205822
Perimeter: p = 23
Semiperimeter: s = 11.5

Angle ∠ A = α = 32.25552404263° = 32°15'19″ = 0.56329601465 rad
Angle ∠ B = β = 73.87223797868° = 73°52'21″ = 1.28993162536 rad
Angle ∠ C = γ = 73.87223797868° = 73°52'21″ = 1.28993162536 rad

Height: ha = 8.64658082329
Height: hb = 4.80332267961
Height: hc = 4.80332267961

Median: ma = 8.64658082329
Median: mb = 5.72327615711
Median: mc = 5.72327615711

Inradius: r = 1.88795235289
Circumradius: R = 4.68443509489

Vertex coordinates: A[9; 0] B[0; 0] C[1.38988888889; 4.80332267961]
Centroid: CG[3.4632962963; 1.60110755987]
Coordinates of the circumscribed circle: U[4.5; 1.30112085969]
Coordinates of the inscribed circle: I[2.5; 1.88795235289]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 147.7454759574° = 147°44'41″ = 0.56329601465 rad
∠ B' = β' = 106.1287620213° = 106°7'39″ = 1.28993162536 rad
∠ C' = γ' = 106.1287620213° = 106°7'39″ = 1.28993162536 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.