In each of the Exercises 1 to 9, find the coordinates of the foci, the vertices, the length of major axis, the minor axis, the eccentricity and the length of the latus rectum of the ellipse: 36x² + 4y² = 144
The given equation is .
Step 1: Converting to standard form
Dividing both sides by 144:
Step 2: Identifying a and b
Since the denominator of is larger than the denominator of , the major axis is along the y-axis.
Comparing with :
- , so
- , so
Step 3: Calculating c and eccentricity
Eccentricity
Step 4: Finding all parameters
- Foci: i.e., and
- Vertices: i.e., and
- Length of major axis: units
- Length of minor axis: units
- Eccentricity:
- Length of latus rectum: units
Explanation
This question requires converting the ellipse equation to standard form to identify the major and minor axes. Since the coefficient of y² has a larger denominator (36 > 4), the major axis is along the y-axis. The solution follows the same method as shown in Example 9 of the textbook context, where comparing denominators determines the axis orientation.
Solution Steps
Step 1: Divide equation by 144 to get standard form x²/4 + y²/36 = 1
Step 2: Identify a² = 36, b² = 4, so a = 6, b = 2 (major axis along y-axis)
Step 3: Calculate c = = = 4
Step 4: Calculate eccentricity e = c/a = 2/3
Step 5: Find foci (0, ±4), vertices (0, ±6), major axis = 12, minor axis = 4, latus rectum = 4/3