Page 121 - TB_5B

Activity 2 Surface Area of Prisms and Pyramids

A rectangular prism has been cut 4 cm 5 cm
5 cm
to make 2 triangular prisms.
3 cm
Find the surface area of the 5 cm

triangular prism. 4 cm

3 cm

Method 1 Use the sum of the areas of faces.
Label all the faces and,tfhinedn tfhinedatrheeasaroefathoef efacehsf.ace.

A A D Face Area(cm2)
D
BC C A 6
B B 20
E F EC 15
D 25
E 6

SSuurrffaaccee aarreeaa AA BB CC DD EE 66 2200 1155 2255 66 7722((ccmm22))

Method 12 Use the sauremasoof fththeeabreaasse oafnfdaclaetse.ral surface.
LTahbeeal raelal tohfethfaecelastearnadl ,sufirnfadcteheF aisreeaqsuoafl thoethfaecseusm. of the areas of faces B,
C, and D. Add all the areas of faces to find the surface area. The length of
face F is the same as the perimeter of the base. Face Area(cm2)

A A6
A B 20

B C D E FacCe Area(c1m5 2)
F A D 6 25

F F E 60 6
A
Surface area A B C D E 6 20 15 25 6 72(cm2)

Surface area A 2 F 6 2 (3 4 5) 5 12 60 72 (cm2)

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