Выражение: ea+pc-qm-pa+qn+cf(векторы)

the kangaroo is a wild animal which has large, powerful hind legs, a long muscular tail and a small head. there are known over 60 different species of kangaroos and close relatives. some of them can be two meters tall with weight up to 90 kg.   the others are much smaller in size. kangaroos are unusual and wonderful animals. kangaroos hop like rabbits to move around quickly. they can jump as far as about three times their own height. they walk on four legs when there is no need to move fast. kangaroos are called marsupials because they carry their babies in a special bag on their paunches. kangaroos are herbivore animals, they eat mainly grass and shrubs. they are common in australia. the kangaroo is one of the most well-known native australian animals. although it can also be found in new guinea kangaroo is the iconic animal of australia. it is even pictured on the coat of arms for australia.

1) диагонали квадрата перпендикулярны, равны и точкой пересечения делятся пополам. bd перпендикулярно mn, bd перпендикулярно ac, следовательно mn паралельно ac. треугольник dac   подобен треугольнику dmn по двум углам, ac : mn = do : db = 1 : 2.ac = bd = 19

mn = 2ac = 38

2) 15+5=20

3) угол cde составляет 2 часть, ∠ade - 7 таких частей, всего 9 частей. угол cde = 90° : 9 = 10°. сумма острых углов прямоугольного треугольника 90°, тогда из треугольник cde: угол dce = 90° - угол cde = 90° - 10° = 80°. диагонали прямоугольника равны и точкой пересечения делятся пополам, тогда треугольник cod равнобедренный (co = od), значит углы при его основании равны: угол ocd = угол odc = 80°.в треугольник ocd находим третий угол: угол cod = 180°   следовательно 180° - 160° = 20° - угол между диагоналями.