Chapter 12.10, Problem 29STP

To determine

To calculate: To choose correct option which gives slant height of pyramid with square base.

Answer to Problem 29STP

  $B)10m$

Explanation of Solution

Given information:

The given information is, Square pyramid is given whose base length is 7m and surface area is $189m^2$ .

Calculation:

Let height of each face be h.

  $\begin{array}{l}then\text{using,}\\ surfacearea=2bh+b^2\\ 189=14h+49\\ \therefore h=10189m\\ Now,byPythagorastheorem,\\ l^2=h^2+\frac{b^2}{4}\\ \therefore l^2=100+12.25\\ \therefore l=10.6m.\\ =10m\end{array}$