Glossary
Absolute Value (in area formula)
Used in the area formula $A=∫_c^d∣f(y)−g(y)∣dy$ to ensure that the difference between the functions is always positive, guaranteeing a positive area.
Example:
In , the absolute value ensures we subtract the 'left' function from the 'right' function to get a positive width for each slice.
Area Between Curves
The total region enclosed by two or more functions over a specified interval, calculated using definite integrals.
Example:
To find the area between curves and , you would integrate the difference of the functions over their intersection interval.
Functions of y
Equations where the independent variable is y and the dependent variable is x, typically expressed in the form $x = f(y)$.
Example:
When calculating the area between and , you are working with functions of y.
Horizontal Slices
A method for approximating the area between curves by dividing the region into infinitesimally thin rectangles oriented horizontally, used when integrating with respect to y.
Example:
When finding the area between and , we use horizontal slices of width and length .
Integrating with respect to y
The process of finding the antiderivative of a function where the variable of integration is y, denoted by $dy$ in the integral.
Example:
To find the area between and , you would set up an integral and perform integrating with respect to y.
Intersection Points
The coordinates where two or more curves meet, found by setting their equations equal to each other and solving for the variable.
Example:
Finding the intersection points of and involves solving , which gives and .
Interval of Integration
The specific range of values (on the x-axis for $dx$ or y-axis for $dy$) over which a definite integral is evaluated to find the area or other quantities.
Example:
If curves intersect at and , then is the interval of integration for finding the area between them.
Upper and Lower Limits (of integration)
The specific values at the top and bottom of the integral sign, representing the boundaries of the interval over which the function is integrated.
Example:
In , is the upper limit and is the lower limit, defining the range of y-values for the area calculation.