Odpowiedź:
a)
x/20 = cos13° ≈ 0,9744
x ≈ 20 * 0,9744 ≈ 19,488
b)
x/8 = sin20° ≈ 0,3420
x ≈ 8 * 0,3420 ≈ 2,736
c)
sin150° + cos120° = sin(180° - 30°) + cos(180° - 60°) = sin30° - cos60° =
= 1/2 - 1/2 = 0
