#### Answer

The equation for trapezoid area $A=\frac{1}{2}a(b_1+b_2)$ is dimensionally correct.

#### Work Step by Step

Equation for area of trapezoid -
$A=\frac{1}{2}a(b_1+b_2)$
LHS - $A$ has SI unit $m^2$.
RHS -
$(b_1+b_2)$ has SI unit $m$.
$a$ has SI unit $m$.
Their product, thus, has SI unit $m^2$.
Both sides have the same units; the equation is dimensionally correct.