13
Пошаговое объяснение:
В трапеции ABCD-равнобедренная проведём высоты BH и BH1. Рассмотрим треугольник ACH1-прямоугольный (угол CH1A=90 градусов), AC=37, AH1=AH+HH1 (так как трапеция ABCD-равнобедренная то AH=H1D=(40-30)/2=5) следовательно AH1=5+30=35 по теореме Пифагора найдём катет CH1: AC^2 =AH1^2 +CH1^2; CH1^2 = sqrt(37^2 -35^2)=144; CH1=12. Рассмотри треугольник СH1D-прямоугольный (угол СH1D=90 градусов), H1D=5 CH1=12 по теореме Пифагора: CD^2 =CH1^2 +H1D^2; CD^2=sqrt(12^2 +5^2)=169; CD=13
ответ: AB=CD=13
To have a pet at home is a very good thing. And it is not important what pet you have. You may have a dog, a cat, a hamster, a parrot or a fish. The most popular pets are cats and dogs.
A cat is good for a small flat, and if you live in a big flat or a house you can keep a dog. It’s much simpler to have a cat because you don’t have to walk a cat every day.
Dogs are best friends of people. These animals are very clever and understand you very well. But you must remember that keeping a dog in a flat is not that easy. You need to walk it two or three times a day. So, you have to get up earlier in the morning and it also takes time to feed the dog. Dogs are hairy animals and they have a specific smell. Nevertheless, dogs are wonderful animals. I love dogs.
People usually keep hamsters, rats, mice and rabbits. These animals are rather easy to look after. These animals are funny, but all they do is eating.
Пошаговое объяснение:
Длина окружности равна C= 2piR. Если её радиус увеличить на 3см, то С1 = 2pi(R+3) = 2piR+6pi. Длина окружности увеличится на 6pi (см).
Аналогично: уменьшив радиус на 3 см, мы уменьшим длину окружности на 6pi (см)
Считая pi=3.14, получим примерно 6pi = 18,84 см
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