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    NationalHardGeometry7–9

    Circle Theorems

    Teoremas do Círculo

    In a circle, an inscribed angle subtends an arc of 140^\circ. What is the measure of the inscribed angle? If a second inscribed angle subtends the same arc, what can you say about the two angles?

    A circle with points B and C on it cutting off a thickened arc at the bottom, labelled 140 degrees. A point A on the far side is joined to both, and the angle at A is marked with a question mark. A second point, joined by dashed lines, gives another angle on the same arc, also marked with a question mark.??A'140°BCA

    An inscribed angle is half the central angle (or half the arc it subtends).

    Solution

    Step 1 of 3

    1. 1.Inscribed angle = \dfrac{140^\circ}{2} = 70^\circ