The base of an isosceles triangle measure $80 cm$ and its area is $360 c{m}^2$. Find the semi perimeter of the triangle.

If the bases of two triangles are situated on the same line and the other vertex of the two triangles are common, then the ratio of the areas of two triangles are _____ to the ratio of their bases.

Area of right triangle$=\frac{1}{2}\times \text{ base }\times \text{ altitude }.$

In $△ PQR, \angle PQR= 90°$and$\overline{QS} \perp \overline{PR }$ .The true relation among the following:

$$\begin{gathered} A) \overline{Q{S}^2} = \overline{PS} \times \overline{SR } \\ B)\overline{ P{Q}^2} =\overline{ RS} \times \overline{PR } \\ C) \overline{Q{R}^2 }= \overline{PS} \times \overline{ SR } \\ D) \overline{PQ} \times \overline{QR} =\overline{QS} \times \overline{PR} \end{gathered}$$

In the figure, $BC=CD=DE$ and$P$  is mid-point of $CD$. The area of $△APC$ is