a) Sketch the graphs of y= tanA and y= secA
b) Prove that secA- tanA= 1 / (secA+tanA)
c) Deduce from parts a) and b) that secA-tanA is greater than 0 and less and equal to 1,
for values of A such that A is greater and equal to 0 and less than and equal to 90 degrees. Explain your reasoning clearly.
d) Given that secA-tanA= 1/2
find the exact value of cosA