Question

9.

Answer 1

Answer:

Slant height (s)= 12.1 cm

Step-by-step explanation:

Given: Base= 4.5 cm.

           Surface area of right square pyramid= 129.5 cm.

First, calculating slant height (s) of right square pyramid.

Surface area of square pyramid= $(a^{2} +2\times a\times s)$

a= side of square base.

s= slant height

∴ $129.5= (4.5^{2} + 2\times 4.5\times s)$

⇒ $129.5= (20.25+2\times 4.5\times s)$

⇒ $129.5= (20.25+9\times s)$

Now, opening the parenthesis and subtracting both side by 20.25.

⇒ $109.25=9\times s$

cross multiplying both side

∴ Slant height (s)= 12.1