Question

what is the surface area of the rectangular prism below? 9 12 15 a. 630 units² b. 846 units² c. 423 units² d. 1260 units²

Explanation:

Step1: Recall surface - area formula

The surface - area formula of a rectangular prism is $SA = 2(lw+lh + wh)$, where $l$ is the length, $w$ is the width, and $h$ is the height. Here, $l = 15$, $w = 12$, and $h = 9$.

Step2: Calculate $lw$

$lw=15\times12 = 180$.

Step3: Calculate $lh$

$lh=15\times9 = 135$.

Step4: Calculate $wh$

$wh=12\times9 = 108$.

Step5: Calculate $lw+lh + wh$

$lw+lh + wh=180 + 135+108=423$.

Step6: Calculate the surface area

$SA = 2(lw+lh + wh)=2\times423 = 846$.

Answer:

B. 846 units²