Plane Geometry
-  ∆ ABC is inscribed in a circle so that BC is diameter. The tangent at a point C intersects BA when produced at a point D. If ∠ABC = 36° then the value of ∠ADC is
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                        View Hint View Answer Discuss in Forum According to question , we draw a figure of ∆ ABC in which inscribed in a circle  
 The angle at the circumference of a semi–circle is a right angle.
 ∴ ∠BAC = 90°
 ∠ABC = 36°
 ∴ ∠ACB = 90° – 36° = 54°
 ∠BCD = 90°Correct Option: DAccording to question , we draw a figure of ∆ ABC in which inscribed in a circle  
 The angle at the circumference of a semi–circle is a right angle.
 ∴ ∠BAC = 90°
 ∠ABC = 36°
 ∴ ∠ACB = 90° – 36° = 54°
 ∠BCD = 90°
 ∴ ∠ACD = 90° – 54° = 36°
 ∠DAC = 90°
 ∴ ∠ADC = 90° – 36° = 54°
-  There are two equal circles of radius 3 cm each and distance between their centres is 10 cm. The length of one of their transverse common tangents is
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                        View Hint View Answer Discuss in Forum As per the given in question , we draw a figure of two equal circles 
 Transverse common tangent = √d² - (r1 + r2)²
 Transverse common tangent = √10² - (3 + 3)²
 [ r1 = r2 = 3 cm.]
 Transverse common tangent = √100 - 36Correct Option: DAs per the given in question , we draw a figure of two equal circles 
 Transverse common tangent = √d² - (r1 + r2)²
 Transverse common tangent = √10² - (3 + 3)²
 [ r1 = r2 = 3 cm.]
 Transverse common tangent = √100 - 36
 Transverse common tangent = √64 = 8 cm.
-  The maximum number of common tangents that can be drawn to two disjoint circles is
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                        View Hint View Answer Discuss in Forum According to question , we draw a figure  Correct Option: CAccording to question , we draw a figure  
 Maximum No. of Common tangents = 4
-  How many common tangents can be drawn on two circles touching each other externally?
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                        View Hint View Answer Discuss in Forum As per the given in question , we draw a figure two circles touching each other externally  Correct Option: DAs per the given in question , we draw a figure two circles touching each other externally  
 No. of common tangents = 3
-  A chord of a circle is equal to its radius. A tangent is drawn to the circle at an extremity of the chord. The angle between the tangent and the chord is
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                        View Hint View Answer Discuss in Forum According to question , we draw a figure of a circle with centre O  
 OB = OC = radii
 ∴ In ∆ OBC,
 OB = BC = COCorrect Option: AAccording to question , we draw a figure of a circle with centre O  
 OB = OC = radii
 ∴ In ∆ OBC,
 OB = BC = CO
 ∴ ∠OCB = ∠OBC = ∠BOC = 60°
 OC ⊥ DE
 ∴ ∠BCD = 90° – 60° = 30°
 
	