Question

zadanie1 oblicz pole i bwód równoległoboku a)dane alfa=45sto h=2 b=6. b)dane alfa=60sto a=4 b=8. bardzo prosze o pomoc zadanie2 oblicz pole i obwód trapezu a) alfa60sto a=4 b=6 b) a=5 c=4 c=4 60sto

Answer 1

z.1

a)

alfa = 45 st

h = 2

b = 6

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P = b*h = 6*2 = 12

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II sposób:

h/a = sin 45 st

2/a = p(2)/2

a p(2) = 2*2

a = 2 p(2)

P = a*b*sin 45 st = 2 p(2)*6* p(2)/2 = 2*6 = 12

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b)

alfa = 60 st

a = 4

b = 8

P = a*b*sin 60 st = 4*8*p(3)/2 = 16 p(3)

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z.2

a)  alfa = 60 st

a = 4

b = 6

Musi to być trapez równoramienny.

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x = ( b - a)/2 = 2/2 = 1

h - wysokość trapezu

x/c = cos 60 st

1/c = 1/2

c = 2

=====

h^2 = c^2 - x^2 = 2^2 - 1^2 = 4 - 1 = 3

h = p(3)

Pole trapezu

P = 0,5*[a + b]*h

P = 0,5*[4 + 6]*p(3) = 5 p(3)

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b)

a = 5

c = 4

alfa = 60 st

Musi to byc trapez równoramienny

Mamy

h/c = sin 60 st

h/4 = p(3)/2

2h = 4 p(3)

h = 2 p(3)

========

x^2 = c^2 - h^2

x^2 = 4^2 - ( 2p(3))^2 = 16 - 12 = 4

x = 2

====

b = a - 2x = 5 -2*2 = 5 - 4 = 1

===========================

Pole

P = 0,5*[a+b]*h

P = 0,5*[5 + 1]*2 p(3) = 6 p(3)

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Zadanie rozwiązano przy założeniu, ze a > b.