$A$ surface is that which has $\ldots \ldots \ldots$ only.

In the Indus Valley Civilisation (about $3000 \, BC$),the bricks used had the ratio of $\ldots \ldots$ for length,breadth,and height,respectively.

Read the following statement:
An equilateral triangle is a polygon made up of three line segments out of which two line segments are equal to the third one and all its angles are $60^{\circ}$ each.
Define the terms used in this definition which you feel necessary. Are there any undefined terms in this? Can you justify that all sides and all angles are equal in an equilateral triangle?

If $PQ = RS$ in the given figure,prove that $PR = QS$. Mention Euclid's axioms used in it.

In the figure,if $OX = \frac{1}{2} XY$,$PX = \frac{1}{2} XZ$ and $OX = PX$,show that $XY = XZ$.

Read the following axioms:
$(i)$ Things which are equal to the same thing are equal to one another.
$(ii)$ If equals are added to equals,the wholes are equal.
$(iii)$ Things which are double of the same thing are equal to one another.
Check whether the given system of axioms is consistent or inconsistent.