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sergij07 [2.7K]
3 years ago
7

If cos x= 5/13 and sin x <0 find cos (x/2) and sin (2x)

Mathematics
1 answer:
taurus [48]3 years ago
4 0
We know that

if cos x is positive
and
sin x is negative
so
the angle x belong to the IV quadrant

cos x=5/13
we know that
sin²x+cos²x=1-------> sin²x=1-cos²x------> 1-(5/13)²---> 144/169
sin x=√(144/169)-------> sin x=12/13
but remember that x is on the IV quadrant
so
sin x=-12/13

Part A) <span>cos (x/2)
cos (x/2)=(+/-)</span>√[(1+cos x)/2]
cos (x/2)=(+/-)√[(1+5/13)/2]
cos (x/2)=(+/-)√[(18/13)/2]
cos (x/2)=(+/-)√[36/13]
cos (x/2)=(+/-)6/√13-------> cos (x/2)=(+/-)6√13/13
the angle (x/2) belong to the II quadrant
so
cos (x/2)=-6√√13/13

the answer Part A) is 
cos (x/2)=-6√√13/13

Part B) sin (2x)
sin (2x)=2*sin x* cos x------> 2*[-12/13]*[5/13]----> -120/169

the answer Part B) is 
sin(2x)=-120/169
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Image.......................
babunello [35]

Answer:

10.75

Step-by-step explanation:

The cost of an adult ticket is £6 more than that of a child ticket, so will be shown by c+6.

Now, we are told that the cost of four child tickets and two adult tickets is £40.50, so we can put this in an equation and solve for c:

(c+6)+(c+6)+c+c+c+c=40.50

6c+12=40.50

6c=28.50

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so, a childs ticket is 4.75

now to find the cost of an adult ticket you add 6,

4.75 + 6

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3 years ago
In a school with 200 students, 45% are males. how many males are there.? please help me​
LUCKY_DIMON [66]

Answer:

<u><em>90 males.</em></u>

Step-by-step explanation:

To find the answer we will <u><em>divide 45% by 100</em></u>, and we get <u><em>0.45</em></u>.  Now <u><em>multiply 0.45 by 200</em></u> and you get <u><em>90</em></u>.  Therefore, <u><em>90 males is the answer. </em></u>

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3 years ago
Solve: 8.2 = 3.4 + d d = _____
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Answer:

4.8

Step-by-step explanation:

You just subtract to solve for d so,

8.2 = 3.4 + d

-3.4   -3.4

4.8 = d

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