EXERCISE

Is the statement true or false? Give reasons.

A terminated line can be produced indefinitely on both the sides.

If two circles are equal, then their radii are equal.

Is the statement true or false? Give reasons.

In the following figure, if $\mathrm{A}\mathrm{B}=\mathrm{P}\mathrm{Q}$ and $\mathrm{P}\mathrm{Q}=\mathrm{X}\mathrm{Y},$ then $\mathrm{A}\mathrm{B}=\mathrm{X}\mathrm{Y}$.

Define perpendicular lines. Are there other terms that need to be defined first? What are they, and how might you define them?

Define the term line segment. Are there other terms that need to be defined first? What are they, and how might you define them?

Define radius of a circle. Are there other terms that need to be defined first? What are they, and how might you define them?

Define square. Are there other terms that need to be defined first? What are they, and how might you define them?

Consider the ‘postulates' given below:
There exist at least three points that are not on the same line.
Do the postulates contain any undefined terms? Are these postulates consistent?
Does it follow from Euclid’s postulates? Explain.