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Elenna [48]
3 years ago
6

IS ANYONE GOOD IN LAW OF COSINES..If so ill give brainlest​

Mathematics
1 answer:
marysya [2.9K]3 years ago
6 0

Answer:

X=70.5^o

Step-by-step explanation:

we know that

The formula of the law of cosines is equal to

c^2=a^2+b^2-2(a)(b)cos(C)

where

a, b and c are sides. C is the angle opposite side c

In this context

The formula to calculate the measure of angle X is equal to

YZ^2=XZ^2+XY^2-2(XZ)(XY)cos(X)

substitute the given values

22^2=20^2+18^2-2(20)(18)cos(X)

solve for cos(X)

484=400+324-(720)cos(X)

484=724-(720)cos(X)

(720)cos(X)=724-484

(720)cos(X)=240

cos(X)=240/720

X=cos^{-1}(240/720)=70.5^o

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What is the perimeter P of △DEF to the nearest whole number?
schepotkina [342]

Answer:

perimeter of ΔDEF  ≈ 32

Step-by-step explanation:

To find the perimeter of the triangle, we will follow the steps below:

First, we will find the length of the side of the triangle DE and FF

To find the length DE, we will use the sine rule

angle E  = 49 degrees

e= DF = 10

angle F = 42 degrees

f= DE =?

we can now insert the values into the formula

=  

cross-multiply

f sin 49° = 10 sin 42°

Divide both-side by sin 49°

f = 10 sin 42° / sin 49°

f≈8.866

which implies DE ≈8.866

We will now proceed to find side EF

To do that we need to find angle D

angle D + angle E + angle F = 180°  (sum of interior angle)

angle D + 49° + 42° = 180°

angle D + 91° = 180°

angle D= 180° - 91°

angle D = 89°

Using the sine rule to find the side EF

angle E = 49 degrees

e= DF = 10

ange D = 89 degrees

d= EF = ?

we can now proceed to insert the values into the formula

=  

cross-multiply

d sin 49° = 10 sin 89°

divide both-side of the equation by sin 49°

d= 10 sin 89°/sin 49°

d≈13.248

This implies that length EF = 13.248

perimeter of ΔDEF = length DE + length EF + length DF

                                  =13.248   +  8.866  + 10

                                   =32.144

                                    ≈ 32 to the nearest whole number

perimeter of ΔDEF  ≈ 32

6 0
3 years ago
How to graph y=-3x+15
steposvetlana [31]

Answer:

Well first you put the y-intercept on the graph. In this case it would be 15

So graph the point (0,15)

The you do the slope which is 3

so you always do rise over run for slope.

If 3 were a fraction it would be 3/1 so go up 3 points and the go right 1 point from (0,15)

hope this helps .-.

3 0
3 years ago
Use the coordinate plane to plot the points (6, 0) and (0, 5). Which statement is true? (0, 5) is located on the x-axis. (0, 5)
m_a_m_a [10]

Answer:

(6, 0) is located on the x-axis

Explanation:

For a point to be on the x-axis, its y-value must equal 0. (6, 0) has an x-value of 6 and a y-value of 0.

"(0, 5) is located at the origin" is not true because the origin is at (0, 0).

"(0, 5) is located on the x-axis" is not true because its y-value is 5, not 0.

"(6, 0) is located at the origin" is not true because the origin is at (0, 0).

6 0
2 years ago
36% of what number is 18?
34kurt
18 * 100 / 36 = 200

<span>36% of 50 is 18</span>
7 0
3 years ago
Read 2 more answers
What is an equation of the line that passes through the points (0,-5) and (-6,0)?
charle [14.2K]

Answer:

y=-5/6x-5

Step-by-step explanation:

0-(-5)/-6-0

-5/6 slope

y-(-5)=-5/6(x-0)

y+5=-5/6x

y=-5/6x-5

8 0
2 years ago
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