5 Write a word from the box in each gap. fact.grow • lick • lifetime memory sweet
Horses are amazing animals! They have a great (1)
and they can remember people,
places and things that happen to them during their whole (2)
. They are quite
friendly too. They aren't often scared of people and they can (3)
food from a person's
hand while they stand in front of them. They are very (4) ►
animals when they are
young. They really like to play! They (5)
quite fast and they become adults after
about four or five years. An interesting (6)
is that horses only sleep for about three
hours a day, and they usually sleep while they are standing. Imagine people doing that! No need
for beds!
Пусть угол при основании х, тогда угол между высотой и боковой стороной равнобедренного треугольника равен (х-15°).
Угол при вершине в два раза больше 2(х-15°)
Сумма углов треугольника равна 180°
х+ х+2·(х-15°)=180°
4х=210°
х=52,5°
х-15°=52,5-15=37,5°
Угол при вершине равнобедренного треугольника в 2 раза больше, так как высота равнобедренного треугольника является также и биссектрисой.
ответ. углы при основании 52,5°; 52,5° и угол при вершине 75°