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prove that the circle drawn on any one of the equal sides of an isosceles triangle as diameter bisects the third side of the triangle. |
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Answer» PROVE that the circle drawn on any ONE of the equal sides of an isosceles triangle as diameter bisects the THIRD side of the triangle.
A ∆ABC in which AB=AC an a circle is drawn with AB as diameter, intersecting BC at D. BD=CD. Join AD we have that an angle in a semicircle is a right angle. ∴ ∠ADB=90°. ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀....(i) Also, BDC being a straight LINE, we have ⠀⠀⠀⠀⠀⠀⠀∠ADB+∠ADC = 180° ==>90°+∠ADC=180° ⠀⠀[Using (i) ] ==>∠ADC = 90°. Now, in ∆ADB and ∆ADC , we have AB=AC ⠀⠀⠀⠀⠀⠀[given] ∠ADB = ∠ADC ⠀[each equal to 90°] AD=AD ⠀⠀⠀⠀⠀⠀[common] ∴∆ADB ≅ ∆ADC⠀⠀⠀⠀ [by RHS-congruence]. Hence,BD=CD |
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