Question

qual e a área de losango cujas diagonais medem 15 cm por 42 cm?

Answer 1

A = D . d
          2

A = 42. 15
           2

A =  315

Answer 2

$\sf A=\dfrac{D\cdot d}{2}$

$\sf A=\dfrac{42\cdot15}{2}$

$\sf A=21\cdot15$

$\boxed{\boxed{\sf A=315\,cm^2}}$