Show that sec⁴θ-tan⁴θ = 1+2tan²θ.
- (a)Show that sec⁴θ-tan⁴θ = 1+2tan²θ.[3]
Mark scheme
Marking points from the official mark scheme (Oct/Nov 2024). The mark or mark type is shown in brackets.
- [M1] Factorise (sec²θ-tan²θ)(sec²θ+tan²θ) Or obtain an expression in cos² θ or sec² θ Or -1 + (2/cos² θ) OE.
- [M1] Use of 1+tan²θ = sec²θ (anywhere) The 2 method marks can appear in either order, in which case the 2nd M1 is for expanding (1 + tan² θ)² - tan⁴ θ.
- [A1] Obtain 1×(1+tan²θ+tan²θ)=1+2tan²θ Obtain given answer from full and correct working.
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 →