Jess bought a crystal that is a pyramid with the slant height of 12 cm and the rectangular base with side lengths of 9 cm and 8 cm. Let's draw a diagram for this situation.
Now, we want to find the surface area of the crystal. We can do this using a known formula. In this formula P is the perimeter of the base, l is the slant height, and B is the area of the base.
S=B+1/2Pl
The base of the pyramid is a rectangle with the side lengths of 9 centimeters and 8 centimeters. Let's calculate its perimeter!
P=2(a+b) ⇒ P&=2( 9+ 8)
&= 34cm
Next, remember that the area of the rectangle is calculated by multiplying the rectangle's sides lengths.
B=a* b ⇒ B&= 9* 8
&= 72cm^2
Let's substitute all of these values into the formula for the surface area and calculate it.
