
A line meets the coordinate axes in A and B. A circle is circumscribed about the triangle OAB. If m and n are the distances of the tangent to the circle at the origin from the points A and B respectively, the diameter of the circle is
A. m(m + n)
B. m + n
C. n(m + n)
D.
Answer
494.1k+ views
Hint: Here, we first find the centre of the circle and obtaining this we can easily find the radius of the circle. Using the equation of tangent passing through the circle, we can find the lengths m and n. As we know that diameter of a circle is twice its radius, so using this we can calculate diameter.
Complete step-by-step answer:
Given coordinates of A is (a, 0) and that of B is (0, b).
Since ∠AOB = , as given that the line AB is a diameter of the circle circumscribing the triangle OAB, its centre is the mid-point of AB, i.e., , and its radius is . Therefore, the equation of the circle through O, A and B is and the equation of the tangent at the origin to this circle is ax + by = 0.
If AL and BM are the perpendiculars from A and B to this tangent, then
and
Hence, m + n is the diameter of the circle.
So, the correct answer is “Option B”.
Note: In these types of questions, first estimation the lengths of different lengths using properties. As in coordinate geometry, coordinates itself associated with length calculate length whenever find coordinates of the endpoint of line. Careful about the equation of the circle, because the standard equation is only when the centre is origin. Tangent to the circle is always perpendicular at the point of contact. Always remember the radius of a circle is half the diameter of the circle. In coordinate geometry, we can say that the centre of a circle is the midpoint of endpoints of diameter of circle.
Complete step-by-step answer:
Given coordinates of A is (a, 0) and that of B is (0, b).
Since ∠AOB =
If AL and BM are the perpendiculars from A and B to this tangent, then
Hence, m + n
So, the correct answer is “Option B”.
Note: In these types of questions, first estimation the lengths of different lengths using properties. As in coordinate geometry, coordinates itself associated with length calculate length whenever find coordinates of the endpoint of line. Careful about the equation of the circle, because the standard equation is only when the centre is origin. Tangent to the circle is always perpendicular at the point of contact. Always remember the radius of a circle is half the diameter of the circle. In coordinate geometry, we can say that the centre of a circle is the midpoint of endpoints of diameter of circle.
Recently Updated Pages
Master Class 12 Business Studies: Engaging Questions & Answers for Success

Master Class 12 English: Engaging Questions & Answers for Success

Master Class 12 Economics: Engaging Questions & Answers for Success

Master Class 12 Social Science: Engaging Questions & Answers for Success

Master Class 12 Maths: Engaging Questions & Answers for Success

Master Class 12 Chemistry: Engaging Questions & Answers for Success

Trending doubts
Which of the following districts of Rajasthan borders class 9 social science CBSE

What is 85 of 500 class 9 maths CBSE

Who is called the Father of Indian Civil Service A class 9 social science CBSE

Which states of India have a common border with Pakistan class 9 social science CBSE

What is the full form of pH?

Latitudinal and Longitudinal extent of India is 30 class 9 social science CBSE
