Thank you for reporting, we will resolve it shortly
Q.
In a triangle $ABC$, if $|\overrightarrow{ BC }|=8,|\overrightarrow{ CA }|=7$,
$|\overrightarrow{ AB }|=10$, then the projection of the vector $\overrightarrow{ AB }$
on $\overrightarrow{ AC }$ is equal to :
$|\vec{ a }|=8,|\vec{ b }|=7,|\vec{ c }|=10$
$\cos \theta=\frac{|\vec{b}|^{2}+|\vec{c}|^{2}-|\vec{a}|^{2}}{2|\vec{b}||\vec{c}|}=\frac{17}{28}$
Projection of $\vec{ c }$ on $\vec{ b }$
$=|\vec{ c }| \cos \theta$
$=10 \times \frac{17}{28}$
$=\frac{85}{14}$
