Geometry II (AQA GCSE Further Maths): Flashcards

Unknown sides or angles in any triangle

Two sides + included angle OR all three sides known

$a^2 = b^2 + c^2 - 2bc \cos A$

$\cos A = \frac{b^2 + c^2 - a^2}{2bc}$

Side-Angle-Side; use to find a side length

Side-Side-Side; use to find an angle

Lowercase = side lengths; Uppercase = opposite angles

$b^2 = a^2 + c^2 - 2ac \cos B$

Pythagoras with an extra correction term

Forgetting to square root the result

An obtuse angle (greater than 90°)

Any triangle: acute, obtuse, or right-angled