Pyramid 8

Calculate the volume and the surface area of a regular quadrangular pyramid with a base side of 9 cm and a side wall with the base has an angle of 75°.

Correct answer:

V =  641.27 cm3
S =  516.1171 cm2

Step-by-step explanation:

a=9 cm S1=a2=92=81 cm2 s=a/2=9/2=29=4.5 cm h=2 s tan75°=tan5π/12=23.75063 cm h2=h2+s2=23.75062+4.5224.1732 cm  V=31 S1 h=31 81 23.7506=641.27 cm3
S2=a h2/2=9 24.1732/2108.7793 cm2  S=S1+4 S2=81+4 108.7793=516.1171 cm2



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