1) 2tan15° –––––––– 1–2tan²15° 2) sin40° + cos310° –––––––––––––––––– 2sin20° cos20° 3) sin50° + cos320° –––––––––––––––––– 2sin25° cos25° 4) 2 / cos²80° – sin²80° ––––––––––––––––––––– cos160° – sin110°