1. Equation of AD (median) Strategy…. 1.Find midpoint D 2.Find eq’n of AD by -Find slope “m” of AD using A & D -Plug “m” & point A or D into y=mx+b & solve for “b” -Now write eq’n using “m” & “b” Remember – the centroid is useful as the centre of the mass of a triangle – you can balance a triangle on a centroid!

2. Centroid Eq’n AD – Midpoint of BC

3. Centroid Eq’n AD – Slope of AD

4. Centroid Eq’n AD – Finding “b”

5. Centroid Eq’n AD – Equation

6. Equation of altitude AD Strategy…. 1.Find “m” of BC 2.Take –ve reciprocal of “m” of BC to get “m” of AD 3.Find eq’n of AD by -Plug “m” from 2. & point A into y=mx+b & solve for “b” -Now write eq’n using “m” & “b”

7. Orthocentre Eq’n AD – Slope of BC then Slope of AD

8. Orthocentre Eq’n AD – Finding “b”

9. Orthocentre Eq’n AD – Equation

10. Equation of ED (perpendicular bisector) Strategy… (use A (-1, 4), B (-1, -2) & C(5, 1)) 1.Find midpoint D 2.Find eq’n of ED by -Find slope “m” of BC using B & E -Take –ve reciprocal to get “m” of ED -Plug “m” ED & point D into y = mx+b & solve for b -Now write eq’n using “m” & “b”

11. Circumcentre eq’n ED – Midpoint of BC

12. Circumcentre Eq’n ED – Slope of BC & Slope of ED

13. Circumcentre Eq’n ED – Finding “b”

14. Circumcentre Eq’n ED – Equation