Study notes

Trigonometry, Bearings & 3D

Sine rule, cosine rule, and the area formula for non-right-angled triangles, three-figure bearings, and 3D problems solved by finding the right 2D triangle inside a solid.

What this topic covers

  • Right-angled trig is not enough for every triangle
  • The sine rule links a side to its opposite angle
  • The cosine rule links all three sides to one angle
  • Area of a triangle without a right angle
  • A three-figure bearing is measured clockwise from North
  • 3D problems: pick the right 2D triangle first

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