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Identify the lateral area and surface area of a regular square pyramid with base edge length 5 in. and slant height 9 in.

a L = 90 in2 ; S = 115 in2
b L = 120 in2 ; S = 162 in2
c L = 180 in2 ; S = 205 in2
d L = 225 in2 ; S = 250 in2

Respuesta :

mreijepatmat
Note that a squared pyramid has a square base & 4 equal triangles.
To find the lateral the lateral area you calculate the area of the 4 equal triangles  and to find the surface area (total Area) you add the area of the base:

Area of each triangle = side (5) x slant (9) and you divide by 2

==>Aera of 1 triangle = (9x5)/2 = 45/2 & for the 4 triangles

Lateral area = (45/2) x 4 = 90 in²

Now the base area (square) = 5 x 5= 25 in²

so the surface area = 90+25 = 115 in² (answer a)

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