Arm 2

**Measure angle using angle tool

Arm 1

**Formation of angle- move one point to show formation

**Vary the arm lengths

Introducing Angle formation

Show interior angle

Show exterior angle

Show points

Arm2 = 10 (slider from 0 to 15, step 1)
Curve(x) = NaN
Arm1 = 9 (slider from 0 to 15, step 1)
D = (5.338749080443048, 0.10172846400210317)
E = Point(Circle[D, Arm1])
a = Segment(D, E)
I = Point(Circle[D, Arm2])
b = Segment(D, I)
α = Angle(I, D, E)
β = Angle(E, D, I)
c = true
d = false
e = true

Tool: SquareTool
Tool2[ <Number>, <Point> ]
Input: side, A
Output: poly1

B = Point(Circle[A, side])
a = Segment(A, B)
c = Circle(A, side)
b = OrthogonalLine(A, a)
C = Intersect(c, b, 2)
d = Circle(C, side)
e = OrthogonalLine(C, b)
D = Intersect(d, e, 1)
poly1, a_1, b_1, d_1, c_1 = Polygon(A, B, D, C)