Answer:
50°
Step-by-step explanation:
As usual, the diagram is not drawn to scale.
The chord divides the circle into two arcs that have a sum of 360°. If we let "a" represent the measure of the smaller arc, then we have ...
a + (a+160°) = 360°
2a = 200° . . . . . . . . . . . subtract 160°
a = 100°
The measure of the angle at A is 1/2 the measure of the subtended arc:
acute ∠A = a/2 = (1/2)·100° = 50°
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<em>Comment on this geometry</em>
Consider a different inscribed angle, one with vertex V on the circle and subtending the same short arc subtended by chord AB. Then you know that the angle at V is half the measure of arc AB. This is still true as point V approaches (and becomes) point A on the circle. When V becomes A, segment VA becomes tangent line <em>l</em>, and you have the geometry shown here.
