Plane Geometry
-  Number of circles that can be drawn through three non-collinear points is :
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                        View Hint View Answer Discuss in Forum One and only one circle can pass through three non-collinear points. Correct Option: AOn the basis of given question , 
 We can say that One and only one circle can pass through three non-collinear points.
-  The length of a chord which is at a distance of 12 cm from the centre of a circle of radius 13 cm is
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                        View Hint View Answer Discuss in Forum As per the given in question , we draw a figure of a circle with centre O,  
 OC ⊥ AB
 ∴ AC = CB
 OA = 13 cm. , OC = 12 cm.
 In ∆ OAC, AC = √OA² - OC²
 AC = √13² - 12²Correct Option: AAs per the given in question , we draw a figure of a circle with centre O,  
 OC ⊥ AB
 ∴ AC = CB
 OA = 13 cm. , OC = 12 cm.
 In ∆ OAC, AC = √OA² - OC²
 AC = √13² - 12²
 AC = √(13 + 12)(13 - 12)
 AC = √25 = 5 cm.
 ∴ AB = 2 AC = 10 cm.
-  Points P, Q and R are on a circle such that∠PQR = 40° and ∠QRP = 60°. Then the subtended angle by arc QR at the centre 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 ,  
 In ∆ PQR,
 ∠PQR = 40° ; ∠QRP = 60°
 ∴ ∠QPR = 180° – 60° – 40° = 80°Correct Option: DAccording to question , we draw a figure of a circle with centre O ,  
 In ∆ PQR,
 ∠PQR = 40° ; ∠QRP = 60°
 ∴ ∠QPR = 180° – 60° – 40° = 80°
 ∴ Angle subtended at the circumference by arc QR = 80°
 ∴ Angle subtended at the centre by arc QR = ∠QOR = 2∠QPR = 2 × 80° = 160°
-  Two circles touch each other externally. The distance between their centres is 7 cm. If the radius of one circle is 4 cm, then the radius of the other circle will be
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                        View Hint View Answer Discuss in Forum On the basis of question we draw a figure of two circles touch each other externally ,  Correct Option: AOn the basis of question we draw a figure of two circles touch each other externally ,  
 We know that , Distance between two circles = OO' = r1 + r2 = 7 cm.
 r1 = 4 cm.
 ∴ r2 = (7 – 4) cm. = 3 cm.
-  The length of the radius of a circle with centre O is 5 cm and the length of the chord AB is 8 cm. The distance of the chord AB from the point O is
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                        View Hint View Answer Discuss in Forum On the basis of question we draw a figure of a circle with centre O and radius is 5 cm ,  
 Here , OA = radius = 5 cm.
 OC ⊥ AB∴ AC = CB = 8 = 4 cm. 2 
 In right angle ∆ OAC,
 Correct Option: BOn the basis of question we draw a figure of a circle with centre O and radius is 5 cm ,  
 Here , OA = radius = 5 cm.
 OC ⊥ AB∴ AC = CB = 8 = 4 cm. 2 
 In right angle ∆ OAC,
 OC = √OA² - AC² = √5² - 4²
 OC = √25 - 16 = √9 = 3 cm.
 
	