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Mashcka [7]
3 years ago
8

Show that (3cosx+sinx) (cosx+3sinx)=3+5sin2x

Mathematics
1 answer:
givi [52]3 years ago
5 0
(3 \cos x+ \sin x) (\cos x+3\sin x) = \\  \\  =  3 \cos^{2} x + 9 \cos x \sin x + \cos x \sin x + 3 \sin ^{2} x =  \\  \\  = 10 \cos x \sin x +3 \underbrace{(\sin ^{2} x + \cos ^{2} x)}_{=1}   =\boxed{5 \sin x + 3  }

---------------------------------------------------------

\sin (2x) = 2 \cos x \sin x

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The perimeter of the rectangle below is 90 units. find the length of side vy . write your answer without variables.
Salsk061 [2.6K]
The picture in the attached figure

we know that
perimeter of a rectangle=2*[base+height]
base=3y+1
height=2y+3
perimeter=90 units
so
90=2*[(3y+1)+(2y+3)]-----> 90=2*[5y+4]----> 10y+8=90----> y=8.2 units

base=3y+1-----> base=3*8.2+1-----> 25.6 units
height=2y+3----> height= 2*8.2+3---> 19.4 units 

the answer is
<span>the length of side vy is (2y+3)-----> 19.4 units</span>

3 0
3 years ago
A total of 765 tickets were sold for the school play. They were either adults or students tickets. There were 65 more student ti
Brrunno [24]

Answer: 350 adult tickets

Step-by-step explanation:

(omg I remember this question!)

  • a stands for the number of adult tickets sold

student tickets : a + 65

<em>the equation for the prob: </em>

765 = a + (a + 65)

<em>solve:</em>

combine 'like terms'

1.) 765 = a + a + 65

2.) 765 = 2a + 65

<u>- 65         - 65 </u>

700= 2a

divide by 2

700/2 = 2a/2

<em>(700/2 = 350) </em>

<em>(the "2" in 2a is cancelled out by the other 2)</em>

<u>350 = a </u>

7 0
3 years ago
The result of adding a complex number to its conjugate is “an integer/a pure imaginary number/a real number/a whole number” and
sineoko [7]

Answer:

If Z is a complex number:

Z = a + b*i

where a and b are real numbers, and i is an imaginary number.

Then "a" is the real part.

"b*i" is the imaginary part.

The conjugate of Z is:

Zc = a - b*i

So the sign of the imaginary part changes.

Then:

Sum:

Z + Zc = (a + bi) + (a - bi) = 2*a + 0 = 2*a

and remember that a is a real number, then 2*a is also a real numer.

The correct answer is "A real number".

Difference:

Z - Zc = (a + bi) - (a - bi) = 2b*i

and this is a pure imaginary number, so here the correct answer is: "a pure imaginary number"

6 0
3 years ago
PLEASE HELP NTH TERM MATHS
fredd [130]

Answer:

odd numbers

Step-by-step explanation:

4 - 7 is 3, 7 - 12 is 5, 12 - 19 is 7, 19 to 28 is 9

So just keep counting

4 0
3 years ago
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Roberta is thinking about joining the food co-op store. If she pays $10.00 to join, she will get 10% off on all the groceries sh
nikitadnepr [17]
She has to buy $100.00 worth of groceries before her savings equals the membership fee.
4 0
3 years ago
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