Area of a circle: πr²

Data:
diameter: 21 cm
radius=diameter/2=21 cm/2=10.5 cm

area of this circle: π(10.5 cm)²=110.25π cm² (≈346.36 cm²)

Answer: area=110.25π cm²

4 0

3 years ago

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.Resolva as equações, sendo U = Q (separe as respostas por vírgulas). A) 3y - 2 = - y + 4 B) 5 - 4x = x + 3 + 2x C) - 12 - 9x =

Oxana [17]

Answer:

$(A) y=1.5$

$(B)x=\dfrac27$

$(C)x=2\dfrac23$

$(D)x=-5.25$

Step-by-step explanation:

(A)

$3y - 2 = - y + 4\\3y+y=4+2\\4y=6\\y=\dfrac64\\\\y=1.5$

(B)

$5 - 4x = x + 3 + 2x\\5 - 4x = 3 +3x\\5-3=3x+4x\\7x=2\\x=\dfrac27$

(C)

$-12 - 9x = - 4 - 12x\\-9x+12x=-4+12\\3x=8\\x=\dfrac83\\\\x=2\dfrac23$

(D) $- x - 6 + 3x = -2x + 8x + 15$

$2x-6 = 6x + 15\\2x-6x=15+6\\-4x=21\\x=\dfrac{21}{-4} \\\\x=-5.25$

5 0

3 years ago

A jar contains six blue marbles and five red marbles. Suppose you choose a marble at random, and do not replace it. Then you ch

TEA [102]

The jar has 6+5=11 marbles.

We have to find the probability of the following event:

1.We pick a marble from a jar that has 11 marbles in total, 5 of them are red

2.We pick a marble from a jar that has now 10 marbles in total, 4 of them are red (because in the previous step we picked a red marble and did not put it back in the jar)

The probability of the first event is:

$P_1=\frac{5}{11}$