Trigonometric identities

What is the value of tan 65° + 2tan 45° - 2tan 40° – tan 25°?

If tan^–1 k + tan^-1 1/2 =π/4

Direction for Questions (41-43):

 Consider the following for the three (03) items that follow: Let p = sin 35°, q = sin 25° and r = sin(–95°).

What is (p + q + r) equal to?

Direction for Questions (41-43):

Consider the following for the three (03) items that follow: Let p = sin 35°, q = sin 25° and r = sin(–95°).

 What is (pq +qr + rp) equal to?

Direction for Questions (44-45): Consider the following for the two (02) items that follow:

Let p = [sin a – sin(a – 90°)].

What is the minimum value of p?