Show that (cos A)/(1 + sin A) + (1 + sin A)/(cos A) can be written in the form p sec A, where p is an integer to be found.
- Show that (cos A)/(1 + sin A) + (1 + sin A)/(cos A) can be written in the form p sec A, where p is an integer to be found.[4]
Mark scheme
Marking points from the official mark scheme (May/June 2014). The mark or mark type is shown in brackets.
- [M1] M1 for obtaining a single fraction, correctly
- [M1] M1 for expansion of (1 + sin A)² and use of identity
- [DM1] DM1 for factorisation and cancelling of (1 + sin A) factor
- [A1] Al for use of 1/(cos A) = sec A and final answer
- [M1] M1 for multiplying first term by (1 - sin A)/(1 - sin A)
- [M1] M1 for expansion of (1 − sin A)(1 + sin A) and use of identity
- [M1] M1 for simplification of the 2 terms
- [A1] A1 for use of 1/(cos A) = sec A and final answer
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