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3 years ago

PLEASE HELP ME GUYS!!

Mathematics

1 answer:

Softa [21]3 years ago

8 0

Answer:

n=20

Step-by-step explanation:

$S_{n} =\frac{n(a_{1}+a_{n})}{2}\\\\1260 =\frac{n(25+101)}{2} \\\\n = 20$

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Vector question. Let v=<-2,1> u=<3,-5> , find:

lyudmila [28]

Answer:

1. ) $\vec {v}.\vec{u}= -11$

2.) The angle between v and u is 147.52°.

Step-by-step explanation:

Given:

$\vec {v}= ( -2 , 1 )\\\vec {u}= ( 3 , -5 )$

To Find:

1. $\vec {v}.\vec{u}= ?$

2. $\theta = ?$

Solution:

$\vec {v}.\vec{u}$ is scalar product given as,

$\vec {v}.\vec{u}=|\vec {v}||\vec {u}|\cos \theta$

$|\vec {v}|=|(-2, 1)|=\sqrt{(-2)^{2} +1^{2}}=\sqrt{5}\\|\vec {u}|=|(3, 5)|=\sqrt{(3)^{2} +(-5)^{2}}=\sqrt{34}$

$\vec {v}.\vec{u}=(-2i +j).(3i-5j)\\$

Here only i.i = j.j =1 and i.j = j.i = 0

∴ $\vec {v}.\vec{u}=(-2\times 3 +1\times -5)\\\vec {v}.\vec{u}=-6-5=-11 \\$

Now, Substituting the above values we get

$-11=\sqrt{5}\times \sqrt{34}\cos \theta\\ \cos \theta=\frac{-11}{\sqrt{170}} \\ \cos \theta =-0.84366\\\therefore \theta =cos^{-1}(-0.84366)\\\therefore \theta =147.52\°$

As it is negative mean $\theta$ is in Second Quadrant Because Cosine is negative in Second Quadrant.

1. ) $\vec {v}.\vec{u}= -11$

2.) The angle between v and u is 147.52°.

5 0

3 years ago

1. i dentify if the following figure is an examle of a parallelogram. show your solution.

Bogdan [553]

The value of the x and y is 12 and -10 respectively, and the provided figure is a parallelogram because the diagonals bisect each other.

<h3>What is parallelogram?</h3>

In two-dimensional geometry, it is a plane shape having four sides, in which two pairs of sides are parallel to each other and equal in length. The sum of all angles in a parallelogram is 360°.

As we know in the parallelogram, the diagonals bisect each other.

Then,

432 = 3x²

x² = 144

x = √144

x = 12

In the parallelogram, the adjacent opposite angles are the same.

∠C+∠B = 240°

= 360 - 240

∠A + ∠D = 120°

∠A = ∠D = 120°/2 = 60

∠D/2 = 60/2 = 3y + 60

3y + 60 = 30

3y = -30

y = -10

From the definition of the parallelogram, the provided figure is a parallelogram.

Thus, the value of the x and y is 12 and -10 respectively and the provided figure is a parallelogram because the diagonals bisect each other.

Learn more about the parallelogram here:

brainly.com/question/1563728

#SPJ1

6 0

2 years ago

Last month, when Joe took his puppy to the veterinarian, the puppy weighed 6.7 pounds. This month, the puppy weighed 10.05 pound

liberstina [14]

Answer:

50%

Step-by-step explanation:

8 0

3 years ago