Question

find the surface area of this figure. sa= a) 148 cm² b) 120 cm² describe the cross - section. b) triangle

Explanation:

Step1: Recall surface - area formula for rectangular prism

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, $l = 6$ cm, $w = 4$ cm, and $h = 5$ cm.

Step2: Calculate each part of the formula

First, calculate $lw$: $lw=6\times4 = 24$ $cm^{2}$. Then, calculate $lh$: $lh = 6\times5=30$ $cm^{2}$. Next, calculate $wh$: $wh = 4\times5 = 20$ $cm^{2}$.

Step3: Substitute into the formula

$SA=2(24 + 30+20)$. First, add the values inside the parentheses: $24 + 30+20=74$ $cm^{2}$. Then, multiply by 2: $SA = 2\times74=148$ $cm^{2}$.

Answer:

a) $148$ $cm^{2}$