We have two right triangles and three different rectangles.
The formula of an area of a right triangle:
[tex]A_T=\dfrac{1}{2}l_1l_2[/tex]
l₁, l₂ - legs
We have l₁ = 20cm and l₂ = 21cm. Substitute:
[tex]A_T=\dfrac{1}{2}(20)(21)=(10)(21)=210\ cm^2[/tex]
The formula of an area of a rectangle:
[tex]A_R=lw[/tex]
l - length
w - width
We have:
rectangle #1: l = 22cm, w = 29cm
[tex]A_{R1}=(22)(29)=638\ cm^2[/tex]
rectangle #2: l = 22cm, w = 21cm
[tex]A_{R2}=(22)(21)=462\ cm^2[/tex]
rectangle #3: l = 22cm, w = 20cm
[tex]A_{R3}=(22)(20)=440\ cm^2[/tex]
The total Surface Area of the triangular prism:
[tex]S.A.=2A_T+A_{R1}+A_{R2}+A_{R3}\\\\S.A.=2\cdot210+638+462+440=1960\ cm^2[/tex]
