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Sine Rule

Learn how to use the Sine Rule, asin⁡A=bsin⁡B=csin⁡C\frac{a}{\sin A} = \frac{b}{\sin B} = \frac{c}{\sin C}, to find missing sides or angles in triangles. Let’s get started! 🚀 🚀

Sine Rule - introduction visual

Video Lesson

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Flashcards

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Sine Rule Formulas for finding missing sides or angles.Sine Rule applied to a triangle with angles 30°, 70°, and one unknown angle, showing how to find the opposite side of 4 cm using the sine rule.Applying the sine rule to find angles with a triangle, with the equation sin(135°)/10 cm = sin(theta)/5 cm.

🛎️ What Is the Sine Rule?

  • The Sine Rule is used to find missing sides or angles in a non-right-angled triangle.
  • The formula is sin⁡Aa=sin⁡Bb=sin⁡Cc\dfrac{\sin A}{a} = \dfrac{\sin B}{b} = \dfrac{\sin C}{c}.

🛎️ Using the Sine Rule to Find a Side

  • You must know one angle and its opposite side as a matching pair.
  • Use this known pair to calculate the missing side opposite another known angle.

🛎️ Using the Sine Rule to Find an Angle

  • You must know one side and its opposite angle as a matching pair.
  • Then apply sin⁡−1\sin^{-1} to find the angle.

Practice Questions

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