Chapter 2, Problem 7RP

To determine

To calculate: The length of EF

Answer to Problem 7RP

The length of EF is $6$ cm

Explanation of Solution

Given information: E divides $\overline{DF}$ into segments in a ratio of $5:2$ and length of $\overline{DF}$ is $21$ cm provided in the question which will help to find the solution.

Calculation: Here, $\frac{DE}{EF}=\frac{5}{2}$ (Given)

and, $\overline{DF}$ = $21$ cm (Given)

So that, $DE+EF=DF$

  →$\therefore EF=6cm$

  →$5DE+2DE=21\times 5$

  →$7DE=21\times 5$

  $DE=15cm$

So that, $\frac{15}{EF}=\frac{5}{2}$

  $\therefore EF=6cm$