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3 years ago

What is the length of DE in the right triangle below ?

Mathematics

2 answers:

NeTakaya3 years ago

5 0

Answer: The length of DE is (B) 25 units.

Step-by-step explanation: As shown in the given figure, ΔDEF is a right-angles triangle, where ∠DFE = 90°, DF = 15 units and EF = 20 units.

We are to find the length of DE.

ΔDEF is right-angled at ∠DFE.

So, using Pythagoras theorem, we have

$DE^2=DF^2+EF^2\\\\\Rightarrow DE^2=15^2+20^2\\\\\Rightarrow DE^2=225+400\\\\\Rightarrow DE^2=625\\\\\Rightarrow DE^2=25^2\\\\\Rightarrow DE=25.$

Therefore, the length of DE is 25 units.

Thus, (B) is the correct option.

olganol [36]3 years ago

3 0

B.25
sorry if my writing is not clear

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Running from the top of a flagpole to a hook in the ground there is a rope that is 13 meters long. If the hook is 5 meters from

bagirrra123 [75]

Answer:

12 meters

Step-by-step explanation:

Looking at the problem we can see that it typifies a right angled triangle. The rope running from the top of the flagpole to the hook on the ground is the hypotenuse of the triangle. Let us call this hypotenuse c. Let the distance between the hook and the foot of the flagpole be b. Let the height of the flagpole be a.

From Pythagoras theorem;

c^2 = a^2 + b^2

a^2= c^2 - b^2

a= √c^2-b^2

From the question

c= 13 metres

b= 5 metres

a= the unknown

a= √c^2-b^2

a= √(13)^2 - (5)^2

a= √169 - 25

a= √144

a= 12 meters

6 0

3 years ago

Read 2 more answers

Solve the system by graphing. Write the solution as an ordered pair. y = 1/3x + 2 y = –x – 2

Dima020 [189]

ANSWER

The solution is where the two graphs intersect, which is
$(-3,1).$

EXPLANATION

The given system of equations are
$y = \frac{1}{3} x + 2$
and

$y = - x - 2$

We need to graph the two equations.

Let us graph

$y = \frac{1}{3} x + 2$
first.

We need at least two points.

You can choose any appropriate value for x and solve for y. Choosing zero makes our working easier. So let us plot the intercepts.

When
$x = 0$

$\Rightarrow \: y = \frac{1}{3} (0) + 2$

$\Rightarrow y = 0 + 2$

$\Rightarrow y = 2$

So this gives us the ordered pair,

$(0,2)$

When
$y = 0$
we get,

$0= \frac{1}{3} x + 2$

$\Rightarrow \: - 2 = \frac{1}{3} x$

$\Rightarrow \: - 2 \times 3= x$

$\Rightarrow \: -6= x$
This also gives the ordered pair

$(-6,0).$

We plot these two points and draw a straight line through them to obtain the blue graph in the attachment.

For the second line

$y = - x - 2$

We again find the intercepts and plot them.

When
$x = 0$

$y = - 0 - 2$

$\Rightarrow \: y = - 2$

This gives the ordered pair

$(0,-2)$

Also, when
$y = 0$

then we have,

$0 = - x - 2$

$2 = - x$

$x = - 2$

Then we again have the ordered pair,

$(-2,0)$

We plot these two points on the same graph sheet to obtain the red graph above.

The intersection of the two lines is
$(-3,1)$

You will get good grades so don't worry much.

4 0

3 years ago

What’s the answer????

serious [3.7K]

Answer:

Step-by-step explanation:

4 0

2 years ago

Read 2 more answers

Please help! Greatly appreciated sorry for really bad quality

Degger [83]

The first answer.

Point P is at (50,-40) the distance from Q to P is 80 units which you can find by subtracting the x of Q (-30) from the x of P (50).
50-(-30)=80
It then tells you point R is vertically above point Q so you know your x value for R will be the same as Q.
Add your distance from Q to P of 80 units to the y value of Q because you are traveling up.
-40+80=40
R will have a point of (-30,40) and a distance of 80 units

7 0

3 years ago

The measure of an exterior angle of a triangle is 3x-5 degrees. The measure of the corresponding interior angle is 5x+17 degrees

adelina 88 [10]

Things to remember the sum of the measures of the interior and exterior angles at each vertex is 180 (supplementary angles) add and equal to 180 3x-5+5x+17= 180 8x+12=180 8x= 168 x=21 substitute in the algebraic expression for exterior angle 3(21) -5= 63-5=58 58 degrees is the exterior angle hope this helps

8 0

3 years ago