Question

In the given figure, $DE\parallel BC$. If $DE=5cm,BC=8cm$ and $AD=3.5cm$, find $AB$.

Answer 1

$DE\parallel BC$

$DE=5cm$

$BC=8cm$

$AD=3.5cm$

Since, $DE\parallel BC$

$\therefore$ $\frac{AD}{AB}=\frac{AE}{AC}=\frac{DE}{BC}$ [ By Thales' theorem ]

$\Rightarrow$ $\frac{3.5}{AB}=\frac{5}{8}$

$\Rightarrow$ $AB=\frac{3.5\times 8}{5}$

$\therefore$ $AB=5.6cm$