Angle sum property of triangle By komal.ggb

Be sure to change the locations of the triangle's WHITE VERTICES each time before dragging the slider!!!

Show alternate angles I

Show alternate angles II

Show parallel lines

A = (16.500717284086843, -1.846723988283025)
B = (13.971010498970102, -5.651737499780938)
C = (19.36493075153307, -5.630830832135345)
t1, c, a_1, b_1 = Polygon(A, B, C)
X_1 = Angle(C, B, A)
D = Midpoint(B, A)
E = Midpoint(C, A)
F = Midpoint(B, C)
Y_1 = Angle(A, C, B)
γ = Angle(B, A, C)
a = 0 rad (slider from 0° to 180°, step 10°)
b = 0 rad (slider from 0° to 180°, step 10°)
H = (-8.56, 0.57)
A' = Rotate(A, a, D)
B' = Rotate(B, a, D)
X_2 = Rotate(C, a, D)
t1', c', a', b' = Polygon(A', B', X_2)
A'_1 = Rotate(A, (-b), E)
B'_1 = Rotate(B, (-b), E)
C'_1 = Rotate(C, (-b), E)
t1'_1, c'_1, a'_1, b'_1 = Polygon(A'_1, B'_1, C'_1)
α = Angle(X_2, B', A')
β = Angle(A'_1, C'_1, B'_1)
sum: α + β + γ
G = Intersect(c', b')
Y_2 = Intersect(c'_1, a'_1)
δ = Angle(C, B, A)
ε = Angle(A, C, B)
text2: "" + α + "+" + β + "+" + γ + "=180°"
f = Line(A, a_1)
X = Point(f)
Y = Point(f)
g = Line(B, f)
ζ = Angle(X, A, B)
θ = Angle(C, A, Y)
e = false
h = false
d = false