O is the centre of the given circle. A tangent PR has been drawn touching the circle at point P. Draw QP ⊥ RP at point P, such that point Q lies on the circle. ∠OPR = 90° (radius ⊥ tangent) Also, ∠QPR = 90° (Given) ∴ ∠OPR = ∠QPR Now, above case is possible only when centre O lies on the line QP. Hence, perpendicular at the point of contact to the tangent to a circle passes through the centre of the circle.
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A depression in the center of the macula of the retina, the area of the most acute vision, where only cones are present and where blood vessels are lacking. Also called central fovea, central pit. fovea is responsible for sharp central vision (also called foveal vision), which is necessary in humans for reading, driving, and any activity where visual detail is of primary importance. Fovea (or Fovea centralis) is the depression in the inner retinal surface, about 1.5 mm wide, the photoreceptor layer of which is entirely cones and which is specialized for maximum visual acuity. |