Basics
It has no parts.
The inclination to one another of two lines in a plane which meet one another and do not lie in a straight line.
What is a plane angle?
It's an extremity of anything.
What is a boundary?
It' a plane figure contained by one line such that all the straight lines falling on it from one point amlong those lying within the figure are equal to one another.
What is a circle?
A trilateral figure with two sides equal.
What is an isosceles triangle?
It has length but not width.
It's an angle contained by straight lines.
What is a rectilineal angle?
They're the extremities of a line.
What are points?
It's a straight l9ine drawn through the center of a circle and terminated in both directions by the circumference of the circle.
What is a diameter?
A trilateral figure with all sides unequal.
What is a scalene triangle?
It has both length and breadth.
What is a surface?
When a line set up on another line makes angles that are equal.
What are right angles?
They're the extremities of a surface.
What are lines?
What is a semicircle?
A quadrilateral figure which is equilateral but not right-angled.
What is a rhombus?
They're the extremities of a line.
What are points?
What is an acute angle?
It's contained by any boundary or boundaries.
What is a figure?
A figure contained by straight lines.
What is a rectilineal figure?
A quadrilateral figure that is right-angled but not equilateral.
What is an oblong?
They're the extremities of a surface.
What are lines?
A straight line that makes right angles with another.
What is a perpendicular?
It's the boundary of a circle.
What is the circumference?
A figure contained by three straight lines.
What is a trilateral figure?
A quadrilateral figure that isn't a square, oblong, rhombus, or rhomboid.
What is a trapezium?