Question

What is the area of an arbitrary elementary vertical strip of height \[y\] and width \[dx\]?

Options

• \[dA=x\cdot dy\]

• \[dA=\int_a^b y\,dx\]

• \[dA=y\cdot dx\]

• \[dA=|A_1|+A_2\]

Answer 1

An elementary vertical strip has height \[y\] and infinitesimally small width \[dx\]. Its area is therefore height multiplied by width, \[dA=y\cdot dx\].