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Course: Class 10 (OD) > Unit 9

Lesson 1: Tangent to a circle
Math
Class 10 (OD)
Tangents to a circle
Tangent to a circle
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Radius perpendicular to tangent line

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Problem

AC↔ is tangent to circle O at point C.
What is the measure of ∠OAC?
  • Your answer should be
  • an integer, like 6
  • an exact decimal, like 0.75
  • a simplified proper fraction, like 3/5
  • a simplified improper fraction, like 7/4
  • a mixed number, like 1 3/4
∘
A circle centered around point O. Segment O C is a radius of the circle. Point A lies outside the circle, and line A C is a line that could potentially be tangent to circle O. A line segment connects point A to point O and intersects the circle at point B. Line segment A O, line segment O C, and line A C create the triangle A O C. Side A O is broken into two line segments, A B and B O. Angle B O C is forty-five degrees.