O-LevelAdditional MathematicsTrigonometry4037/22 · May/June 2016 · Q128 Marks
Solve the equation
- (i)8 sin²A + 2 cosA = 7 for 0° ≤ A ≤ 180°.[4]
- (ii)cosec (3B + 1) = 2.5 for 0 ≤ B ≤ π radians.[4]
Mark scheme
Marking points from the official mark scheme (May/June 2016). The mark or mark type is shown in brackets.
- [B1] 8(1-cos² A) + 2cos A = 7 or better
- [M1] Solves or factorises their 3-term quadratic in cosA
- [A2] 60, 104.477... rounded or truncated to 1 dp or more; with no extras in range; not from clearly wrong working but allow recovery from minor slips or A1 for either, ignoring extras
- [B1] sin(3B + 1) = 0.4 soi may be implied by 1/sin(3B+1) = 2.5
- [M1] [3B + 1 =] 0.41 or better implies B1
- [A2] 0.577, 1.9[0], 2.67 or 0.57669..., 1.89823..., 2.67108... rounded or truncated to 4 or more sf with no extras in range; or A1 for any one correct ignoring extras If M0 then B2 for all 3 correct angles found or B1 for 1 or 2 correct angles found
Write your answer and get it marked
On Oracle Prep you can write or photograph your own answer and have it marked by AI against this mark scheme, with feedback on what you missed.
Sign up free →