38. проводим из вершины высоту (медиана, бис-са), Она пересекает сторону Ас в точке Н. Точка О принадлежит ВН. Медиана делит тр-к на два равновеликих. Площадь исходного тр-ка =12/4 *V(4*10*10-12*12)=3*V256=3*16=48, ее половина 48/2=24. Наша половина состоит из трех треугольников: ВМО, АМО и АНО, Тр-к АМО=АНО по трем сторонам (АО-общая. ОМ=ОН-радиусы, АМ=АН=6 - отрезки касательных из одной точки), они прямоугольные. АН=1/2АС=12/2=6. Находим радиус вписанной окружности=12/2 *V(2*10-12)/(2*10+12)=6V8/32=6V1/4=6/2=3 Samo=Saho=1/2*3*6=9 Samo+Saho=9+9=18 Sbmo=24-18=6 39.аналогично 38 площадь исходного тр-ка =16/2 *V(4*100-256)=8*12=96. половина 48.радиус=16/2*V(2*10-16)/(2*10+16)=8*V4/36=8V1/9=8/3. AH=AM=16/2=8 2Samh=8* 8/3=64/3 Sbmo=48-64/3=80/3 41.R=abc/4S S=Vp(p-a)(p-b)(p-c) a=7x, b=15x, c=20x p=1/2(7x+15x+20x)=21x S=V21x*14x*6x*x=V1764x^4=42x^2 25=7x*15x*20x/42x^2=50x x=0,5 стороны 7*0,5=3,5 15*0,5=7,5 и 20*0,5=10 25=3,5*7,5*10/4S S=262,5/25*4 = 2,625 42, по соотношению сторон (частей) треугольник прямоугольный. Катеты 3х и 4х, гипотенуза 5х. площадь =1/2(3х*4х)=6x^2 6x^2=96 x^2=16 x=4. Гипотенуза 4*5=20, а радиус описанной окружности половина гипотенузы 20/2=10
School is getting more and more equipped with computers. Children spent too much time in front of them and it damages their health I think that the fact that school is getting more and more equipped with computers has more advantages than disadvantages. Firstly, children can find all necessary information in the Internet. It is a lot faster and more effective than searching for it in the library. Secondly, children study the basics of informatisc at school which will help some of the if they choose a career connected with computers. Thirdly, children better learn the material if it is shown as a presentation on a computer because in this case visual memory plays its role. On the other hand, excessive sitting in front of the computer worsens out eyesight a lot. But nowadays there are special monitors which reduce radiation which comes from them. In conclusion, I believe that computers should be in every school as learning with their help is a lot more effective and interesting.
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