EAPCET Mathematics · Intermediate second year · Paper IIB
Ellipse
Ellipse covers the standard ellipse, its eccentricity, foci and directrices, the latus rectum, and tangent conditions.
- Subject
- Mathematics
- Taught in
- Intermediate second year · Paper IIB
- Mathematics in the paper
- 80 of 160 questions
Key formulas and results
- :
- Foci and directrices
- Latus rectum length
- touches the ellipse iff
- Parametric point:
- Sum of the focal distances of any point
- Point of contact of the tangent with :
- Area enclosed by the ellipse :
What this chapter covers
- Standard equation
- Eccentricity, foci and directrices
- Latus rectum
- Parametric form
- Tangents and normals
How it is usually asked
- Find the eccentricity or foci
- Write the equation from given data
- Apply the tangent condition
Understanding Ellipse
An ellipse is the set of points whose distance from a focus is e times the distance from the matching directrix, with 0 < e < 1. Equivalently, the sum of the distances of any point from the two foci is constant, equal to the length of the major axis. In standard form x²/a² + y²/b² = 1 with a > b, the major axis lies along the x-axis and b² = a²(1 − e²).
From a and e everything else follows. The foci are (±ae, 0), the directrices are x = ±a/e, the vertices are (±a, 0) and the latus rectum has length 2b²/a. If instead b > a, the major axis lies along the y-axis and the roles of a and b swap, so the foci move to the y-axis. Always check which denominator is larger before using any formula.
Points on the ellipse can be written as (a cos θ, b sin θ), which simplifies tangent and normal questions. The line y = mx + c touches the ellipse when c² = a²m² + b², and the tangent at (x₁, y₁) is xx₁/a² + yy₁/b² = 1. EAPCET questions ask for eccentricity, foci, latus rectum, an equation from given data or a tangent condition.
Worked example
EAPCET-style question
The foci of the ellipse are
- (1)
- (2)
- (3)
- (4)
Solution
- Divide by 12: .
- The larger denominator 4 is under , so the major axis is along the -axis with semi-major axis 2 and semi-minor axis .
- Distance from centre to each focus , so .
- The foci are .
Answer:
More practice questions
Practice question 1
The area enclosed by the ellipse is
- (1)
- (2)
- (3)
- (4)
Solution
- Divide by 144:
- and
- Area
Answer:
Common mistakes to avoid
- Assuming the major axis is along the x-axis; compare the denominators after making the right side 1.
- Reading a and b before dividing the equation to get 1 on the right side.
- Using b² = a²(e² − 1), the hyperbola relation; for an ellipse b² = a²(1 − e²), so e is always less than 1.
- Taking the latus rectum as 2a²/b; it is 2b²/a, with a the semi-major axis.
How to prepare it
Check whether the major axis is along x or y before using any formula.
Once the formulas feel familiar, test them the way the exam does: practise Ellipse questions chapter-wise, then attempt a full previous year paper to see whether it holds up under a 3-hour timer.
Related Mathematics chapters
- ParabolaIntermediate second year · Paper IIB
- HyperbolaIntermediate second year · Paper IIB
- IntegrationIntermediate second year · Paper IIB
See every chapter in the EAPCET Mathematics syllabus.
Practise Ellipse chapter-wise
Chapter-wise quizzes show exactly which topics in this chapter you still get wrong — before a full paper does.
Frequently asked questions
- Is Ellipse part of the EAPCET Mathematics syllabus?
- Yes. Ellipse is taught in Intermediate second year · Paper IIB Mathematics, and the EAPCET Engineering syllabus is based on the Intermediate first- and second-year syllabus. Check the official notification each year for any changes.
- How should I prepare Ellipse for EAPCET?
- Check whether the major axis is along x or y before using any formula.
- How many Mathematics questions are there in EAPCET?
- 80 of the 160 questions in the Engineering paper are Mathematics, spread across 37 chapters.
- What mistakes do students make in Ellipse?
- Assuming the major axis is along the x-axis; compare the denominators after making the right side 1. Reading a and b before dividing the equation to get 1 on the right side. Using b² = a²(e² − 1), the hyperbola relation; for an ellipse b² = a²(1 − e²), so e is always less than 1. Taking the latus rectum as 2a²/b; it is 2b²/a, with a the semi-major axis.