(cosα+sinα)^2= 1+2sinαcosα= 1+sin2α=49/25

∴√ 2cos (π/4-α) = 7/5 Choose D.

(2) Sine (π/5) Cosine (π/5) Cosine (2π/5)/ Sine (π/5)

=sin(2π/5)cos(2π/5)/2sin(π/5)

=sin(4π/5)/4sin(π/5)

=sin(π/5)/4sin(π/5)= 1/4 Select B (the key is to multiply SIN up and down to start the chain reaction).

(3) One generation at a time

Example a: f (x) = sinx-cosx = √ 2sin (x-π/4).

It can be seen that y=√2sinx has moved π/4 units to the right.

So it is an increasing choice a in this interval.