Answer:
A) 220.5 mm^2
Step-by-step explanation:
Explanation:-
Given A regular triangular pyramid has a base of area is 31.5mm^2
and also given surface area of triangular pyramid is 252 mm ^2
by using formula
surface area of regular triangular pyramid = base of area + half of lateral surface.
[tex]surface area = area of the pyramid X \frac{1}{2} lateral surface[/tex]
252 = 31.5 + [tex]\frac{1}{2} lateral surface[/tex]
[tex]252-31.5= \frac{1}{2} lateral surface[/tex]
220.5 = lateral area of triangular pyramid
lateral area of triangular pyramid = 220.5 mm^2
