C1 fully correct method leading to = or = 2 or (y + 4)2 = 0 or (x 2)2 = 0 and y x –4 – statement, eg only one point of intersection so the line is a tangent to the circle 20 Proof C1 draws and considers angles in an isosceles triangle (algebraic notation may be used, eg OC two angles labelled x) C1 finds sum of angles in triangle eg + + + = 180, or sum of angles at ABC, x x y y O, eg 180 2x + 180 2y – – C1 complete method leading to = 90 ACB C1 complete proof with all reasons given, eg base angles of an isosceles triangle are equal, angles in a triangle add up to 180º, angles on a straight line add up to 180º Paper: 1MA1/3H Question Working Answer Mark Notes 21 for process to find (= b a) or (= a b) – – P1 for process to find (= + a + 2a) or (= a) + 2a) –b –k(b – P1 or (= + a + a) or b + (1 b)) k(b k)(a –b – – – for process to find two of , and P1 for process to find using as a multiple of or using as a multiple of or using as a k, P1 multiple of for oe A1
C1 fully correct method leading to y = –4 or x = 2 or (y + 4)2 = 0 or (x – 2)2 = 0 and statement, eg only one point of intersection so the line is a tangent to the circle 20 Proof C1 draws OC and considers angles in an isosceles triangle (algebraic notation may be used, eg two angles labelled x) C1 finds sum of angles in triangle ABC, eg x + x + y + y = 180, or sum of angles at O, eg 180 – 2x + 180 – 2y C1 complete method leading to ACB = 90 C1 complete proof with all reasons given, eg base angles of an isosceles triangle are equal, angles in a triangle add up to 180º, angles on a straight line add up to 180º Paper: 1MA1/3H Question Working Answer Mark Notes 21 P1 for process to find (= b – a) or (= a – b) P1 for process to find (= –b + a + 2a) or (= –k(b – a) + 2a) or (= –b + a + k(b – a) or b + (1 – k)(a – b)) P1 for process to find two of , and P1 for process to find k, using as a multiple of or using as a multiple of or using as a multiple of A1 for oe
12b_1ma1_3h_-_november_2017_mark_scheme.docx