Triangle formulae

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• Is it a right-angled triangle?

• Does the question include angles?

• Trigonometry sinθ = opp/hyp cosθ = adj/hyp tanθ = opp/adj

• Pythagoras a^2 + b^2 = c^2 c^2 - b^2 = a^2 c^2 - a^2 = b^2

• Cosine rule a^2 = b^2 + c^2 - 2bc CosA A = Cos^-1 ((b^2 + c^2 - a^2)/2bc)

• Sine rule SinA/a = SinB/b = SinC/c a/SinA = b/SinB = c/SinC

• Area of triangle Area = 1/2*a*b*SinC 

• No. of sides and angles

• Yes

• No

• Yes

• No

• 3 sides 1 angle

• 2 sides 2 angles

• 2 sides + angle in between