Plane Geometry
- A circle (with centre at O) is touching two intersecting lines AX and BY. The two points of contact A and B subtend an angle of 65° at any point C on the circumference of the circle. If P is the point of intersection of the two lines, then the measure of ∠APO is
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As per the given in question , we draw a figure circle with centre O ,
Given , ∠ACB = 65°
∠AOB = 2 × ∠ACB = 2 × 65° = 130°Correct Option: A
As per the given in question , we draw a figure circle with centre O ,
Given , ∠ACB = 65°
∠AOB = 2 × ∠ACB = 2 × 65° = 130°
∠OAP = 90°; ∠AOP = 65°
∴ ∠APO = 180° – 90° – 65° = 25°
- Chords AB and CD of a circle intersect externally at P. If AB = 6 cm, CD = 3 cm and PD = 5 cm, then the length of PB is
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According to question , we draw a figure of a circle with two chords AB and CD ,
Given , AB = 6 cm; CD = 3 cm
PD = 5 cm; PB = ?
We know that , PA × PB = PC × PD
⇒ (PB – 6) PB = 2 × 5
⇒ PB² – 6PB – 10 = 0⇒ PB = 6 ± √36 + 40 2
Correct Option: B
According to question , we draw a figure of a circle with two chords AB and CD ,
Given , AB = 6 cm; CD = 3 cm
PD = 5 cm; PB = ?
We know that , PA × PB = PC × PD
⇒ (PB – 6) PB = 2 × 5
⇒ PB² – 6PB – 10 = 0⇒ PB = 6 ± √36 + 40 2 PB = 6 ± √76 = 6 + 8.7 = 7.35 cm 2 2
- If two equal circles whose centres are O and O', intersect each other at the point A and B, OO' = 12 cm and AB = 16 cm, then the radius of the circle is
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On the basis of question we draw a figure of two circles with centres O and O' ,
Here , AB = 16 cm and OO' = 12 cm
AC = BC = 8 cm
OC = CƠ = 6 cm
∴ OA = √OC² + CA²
OA = √6² + 8²Correct Option: A
On the basis of question we draw a figure of two circles with centres O and O' ,
Here , AB = 16 cm and OO' = 12 cm
AC = BC = 8 cm
OC = CƠ = 6 cm
∴ OA = √OC² + CA²
OA = √6² + 8²
OA = √36 + 64
OA = √100 = 10 cm
- Two parallel chords are drawn in a circle of diameter 30 cm. The length of one chord is 24 cm and the distance between the two chords is 21 cm. The length of the other chord is
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As per the given in question , we draw a figure circle
Given , AB = 24 cm
⇒ AE = EB = 12 cm
OE = √OA² - AE²
OE = √15² - 12²
OE = √225 - 144 = √81
OE = 9 cmCorrect Option: B
As per the given in question , we draw a figure circle
Given , AB = 24 cm
⇒ AE = EB = 12 cm
OE = √OA² - AE²
OE = √15² - 12²
OE = √225 - 144 = √81
OE = 9 cm
∴ OF = 21 – 9 = 12 cm
Also, CF = √15² - 12² = 9 cm
∴ CD = 2 × CF = 2 × 9 = 18 cm
- A unique circle can always be drawn through x number of given non-collinear points, then x must be :
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As per the given question ,
One and only circle can pass through three non-collinear points.Correct Option: B
As per the given question ,
We can say that One and only circle can pass through three non-collinear points.