Solids, angles and quadrilaterals · Usually met around P2
Angles and comparing them
How far it opens, not how long its sides are.
How to do it
Method
How far it opens, not how long its sides are
Line up vertex and one side: the one opening further is bigger
Another way
Think of a clock
Minute hand on 12: the hour hand on 3 opens wider than on 2
In full
An angle is made of a point (its vertex) and two straight sides. How big it is depends on how far the sides open, not on how long they are drawn: longer sides don't make a bigger angle. To compare two angles, lay one vertex and one side on top of the other's and look at the other side: the one that opens wider is bigger. Or cut an angle from paper and compare, or think of a clock: the more big steps between the hands, the wider the angle.
Worked examples
Have a go first, then open each one for the answer and the working.
Example 1
How many angles does this shape have?
Show the answer and working
Answer: 5 angles
Each corner where two sides meet is an angle: 5.
Example 2
Angle A is bigger than angle B.
True or false?
Show the answer and working
Answer: False
Look at how far the sides open, not how long they are drawn.
Example 3
2 sheets shaped with 6 sides each have one corner cut off along a straight line (not through another corner). How many angles do they have now altogether?
Show the answer and working
Answer: 14 angles
Each loses 1 angle but gains 2 at the ends of the cut: 6 − 1 + 2 = 7; 2 sheets have 14.
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