Angle in a Semicircle
An angle inscribed in a semicircle is always a right angle:
Why? Because:
The inscibed angle 90° is half of the central angle 180°
(Using "Angle at the Center Theorem" above)
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 | Another Good Reason Why It Works
We could also rotate the shape around 180° to make a rectangle!
It is a rectangle, because all sides are parallel, and both diagonals are equal.
And so its internal angles are all right angles (90°).
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 | Tangent Angle
A tangent is a line that just touches a circle at one point.
It always forms a right angle with the circle's radius, as show
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