1MA0 Higher November 2015 Paper 2 Q15
15
Diagram NOT accurately drawn
\(B\), \(C\) and \(D\) are points on the circumference of a circle, centre \(O\).
\(BOD\) is a diameter of the circle.
\(AO = 7\) cm Angle \(ABO = 90^\circ\) Angle \(OAB = 35^\circ\) Angle \(DBC = 70^\circ\)
*(a) Explain why angle \(BCD\) is \(90^\circ\) (1)
(b) Calculate the length of \(BC\).
Give your answer correct to 3 significant figures. (4)
Give your answer correct to 3 significant figures. (4)
| Answer | Mark | Notes |
|---|---|---|
| 1 | C1 for a complete reason eg Angles in a semicircle are \(90^\circ\), alternate segment theorem |
| Answer | Mark | Notes |
|---|---|---|
| 2.75 | 4 | M1 for \(7 \times \sin 35\) M1 for \(7 \times \sin 35 \times 2\) M1 (indep) for \(\text{``}DB\text{''} \times \cos 70\) A1 2.74 - 2.75 |