Question

me ajudem com esse exercício sobre teorema de tales pfv

Answer 1

a+b=8 cm,então:
$\frac{b}{3x}= \frac{a+b}{x+3x}$
$\frac{b}{3x}= \frac{8}{4x}$
$\frac{b}{3x}= \frac{2}{x}$
$bx=6x$
$b= \frac{6x}{x}$
b=6 cm

a+b=8
a+6=8
a=8-6
a=2 cm

Answer 2

 Do Teorema de Thales,

$\frac{3x}{x+3x}=\frac{b}{a+b}\\\\\frac{3x}{4x}=\frac{b}{8}\\\\\frac{3}{4}=\frac{b}{8}\\\\4b=3\cdot8\\\\4b=24\\\\\boxed{b=6\,\text{cm}}$
 
 Da figura, a + b = 8.

 Por fim,

$a+b=8\\a+6=8\\a=8-6\\\boxed{a=2\,\text{cm}}$