1MA0 Higher November 2015 Paper 1 Q22
*22
Diagram NOT accurately drawn
\(A\), \(B\), \(D\) and \(E\) are points on a circle.
\(ABC\) and \(EDC\) are straight lines.
Prove that triangle \(BCD\) is similar to triangle \(ECA\).
You must give reasons for your working. (5)
| Answer | Mark | Notes |
|---|---|---|
| Similarity and proof | 5 | B1 for method matching a pair of opposite angles, e.g. if \(EAB = x\), \(BDE = 180 - x\), \(EAB + BDE = 180\) B1 for linking angles between quad and triangle, e.g. if \(BDE = 180 - x\) then \(BDC = x\) B1 for stating or implying \(ACE = BCD\) (same angle) C1 for Opposite angles of a cyclic quadrilateral add up to \(180^\circ\) or statement linking three angles for similarity C1 for complete proof |