Eng neers use tr gonometry and other mathemat cal relat onsh ps to f nd very close approx mat ons to lengths and d mens ons . In the des gn of large structures , eng neers must ensure that forces act ng on the structure w ll balance so that they rema n stat onary . Eng neers use tr gonometry to account for vert cal and hor zontal components of the d fferent forces that act on structures , thus determ n ng that the structure w ll be able to stand w thout collaps ng before t s even constructed . These strateg es , based on mathemat cal knowledge , enable eng neers to des gn solut ons to problems that m ght otherw se be unsolvable .