# 16 21 21 triangle

### Acute isosceles triangle.

Sides: a = 16   b = 21   c = 21

Area: T = 155.3321902712
Perimeter: p = 58
Semiperimeter: s = 29

Angle ∠ A = α = 44.78553756108° = 44°47'7″ = 0.78216522612 rad
Angle ∠ B = β = 67.60773121946° = 67°36'26″ = 1.18799701962 rad
Angle ∠ C = γ = 67.60773121946° = 67°36'26″ = 1.18799701962 rad

Height: ha = 19.41664878389
Height: hb = 14.7943514544
Height: hc = 14.7943514544

Median: ma = 19.41664878389
Median: mb = 15.43553490404
Median: mc = 15.43553490404

Inradius: r = 5.35662725073
Circumradius: R = 11.35663277679

Vertex coordinates: A[21; 0] B[0; 0] C[6.09552380952; 14.7943514544]
Centroid: CG[9.03217460317; 4.93111715147]
Coordinates of the circumscribed circle: U[10.5; 4.3266220102]
Coordinates of the inscribed circle: I[8; 5.35662725073]

Exterior(or external, outer) angles of the triangle:
∠ A' = α' = 135.2154624389° = 135°12'53″ = 0.78216522612 rad
∠ B' = β' = 112.3932687805° = 112°23'34″ = 1.18799701962 rad
∠ C' = γ' = 112.3932687805° = 112°23'34″ = 1.18799701962 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.