An angle is a measure of the amount of turn between two lines that meet at a point. It's measured in degrees (°).
Example:
/
/ |
/ |
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The angle between the two lines is represented by the symbol ?.
A triangle is a closed shape with three straight sides and three angles. The sum of all the angles inside a triangle always adds up to 180°.
Example:
A
/ \
/ \
B-----C
In triangle ABC:
?A + ?B + ?C = 180°
If you know two angles in a triangle, you can find the third angle by using the following formula:
Missing angle = 180° - (known angle 1 + known angle 2)
Example:
A
/ \
/ \
B-----C
If ?A = 60° and ?B = 80°, then:
?C = 180° - (60° + 80°) = 40°
Remember to practice using this knowledge to solve problems in your Edexcel GCSE Foundation Maths course!