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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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: D
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°
∴ ∠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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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: D
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 - 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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According to question , we draw a figure
Correct Option: C
According 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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As per the given in question , we draw a figure two circles touching each other externally
Correct Option: D
As 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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According to question , we draw a figure of a circle with centre O
OB = OC = radii
∴ In ∆ OBC,
OB = BC = COCorrect Option: A
According 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°