.Хорда АВ равна 8. Найти радиус окружности, если дуга АВ равна 90 градусов.

8^2=2а^2

64=2а^2

32=а^2

Радиус=2а

Объяснение:

In the evenings            into the city and go clubbing or see a movie.
          a lot of new friends.           my pronunciation is much better already, and                almost everything. On weekdays           Liam. At the moment            on their new website and            help with it.            some useful stuff about how people        business in this country.

              to see me?            the winter holiday skiing with Ryan and Liam.              to meet you and there’s plenty of space. You must bring lots of warm clothes because            really cold here in the winter. Let me know as soon as              . And tell me what           these days.

ответ и Объяснение:

Нужно знать формулы сокращённого умножения:

a) a²-b² = (a-b)·(a+b);

b) (a-b)² = a²-2·a·b+b²;

c) a³+b³ = (a+b)·(a²-a·b+b²);

d) a³-b³ = (a-b)·(a²+a·b+b²);

e) (a-b)³ = a³-3·a²·b+3·a·b²-b³.

1) (a²-3)³-(a-2)·(a²+4)·(a+2) = [e)] = a⁶-3·a⁴·3+3·a²·3²-3³-(a-2)·(a+2)·(a²+4) = [a)] =

= a⁶-9·a⁴+27·a²-27-(a²-4)·(a²+4) = [a)] = a⁶-9·a⁴+27·a²-27-(a⁴-16) =

= a⁶-9·a⁴+27·a²-27-a⁴+16 = a⁶-10·a⁴+27·a²-11;

2) (b²-3)³-(b²+3)(b⁴-3·b²+9) = [e), c)] = b⁶-3·b⁴·3+3·b²·3²-3³-(b⁶+27) =

= b⁶-9·b⁴+27·b²-27-b⁶-27 = -9·b⁴+27·b²-54;

3) (m²-1)(m⁴+m²+1)-(m²-1)³ = [d), e)] = m⁶-1-(m⁶-3·m⁴·1+3·m²·1²-1³) =

= m⁶-1-(m⁶-3·m⁴+3·m²-1) = m⁶-1-m⁶+3·m⁴-3·m²+1 = 3·m⁴-3·m²;

4) (x²-2)·(x⁴+2·x²+4)-(x³-1)² = [d), b)] = x⁶-8-(x⁶-2·x³+1) =

= x⁶-8-x⁶+2·x³-1 = 2·x³-9.