1/10 of what number is 10 times as much as 8

In △ABC, AD and BE are the angle bisectors of ∠A and ∠B and DE ║ AB . Find the length of DE if perimeter of ABDE is 30 cm and AB

-BARSIC- [3]

Answer:

DE = 6 cm

Step-by-step explanation:

Let DE = x cm.

Since DE is parallel to AB therefore by the alternate interior angles theorem, m∠BAD = m∠ADE and m∠ABE = m∠DEB ............(1)

As AD is an angle bisector of ∠A, therefore m∠EAD = m∠DAB ; Since BE is an angle bisector of ∠B ⇒ m∠ABE = m∠EBD.

Therefore, from (1) We get , m∠EAD = m∠ADE and m∠EBD = m∠BED.

So, the triangles ADE and EDB are then isosceles with AE = ED and ED = DB.

So AE = DE = DB = x, and since the perimeter of ABDE is 30 cm, then

12 + x + x + x = 30

⇒ 12 + 3x = 30

⇒ x = 6

Hence, the length of DE is 6 cm.

8 0

3 years ago

Read 2 more answers

Please Help! What is a cubic polynomial function in standard form with zeros –5, –1, and –5?

yan [13]

FIRST. find the factors:
X=-5 --> (X + 5) = 0
x = 1--> (X - 1) = 0
x =3 --> (x - 3) = 0
3
NEXT, multiply all the factors:
(x + 5) (x - 1) (x - 3) = 0
-> X3 + x2 - 17x +15 = 0
-> f(x) = x3 + x2 - 17x +15 or
y=x3 + x2
17x + 15

8 0

2 years ago

Please help !!!!!!!!!!!!

jekas [21]

This is for 2.X=22 so the total angle is 90° and you take away 68° and that leaves you with 22°

6 0

2 years ago

Some students were asked what kinds of animals they have at home.

Nataly_w [17]

(a) Animals by popularity; Dogs, Cats, Others, Horses.

(b) If 250 students were interviewed, 20 students have other pets.

(c) No, it was incorrect.

Step-by-step explanation:

Step 1; We arrange the different pets in chronological order, from the highest percent to the lowest percent;

1. Dogs - 67%,

2. Cats - 20%

3. Others - 8%,

4. Horses - 1%.

None is not included in this list.

Step 2; If 250 students were interviewed, 8% of those have other pets. So we need to calculate how much 8% of 250 is.

8% of 250 = $\frac{8}{100}$ × 250 = 0.08 × 250 = 20.

So 20 students had other pets.

Step 3; 20% of the interviewed students had cats. If 75 students had cats, we need to equate 20% to the 75 and find out how many students were actually interviewed.

20% × x = 75, 0.2 × x = 75,

x = $\frac{75}{0.2}$ = 375.

So if 375 students were interviewed, 75 students would have cats. So the estimate of 250 students being interviewed is incorrect.

8 0

3 years ago

Find x so that the points (x,x+1), (x+2,x+3) and (x+3,2x+4) form a right-angled triangle.

azamat

Let a, b, and c be vectors each starting at the origin and terminating at the points (x, x + 1), (x + 2, x + 3), and (x + 3, 2x + 4), respectively.

Then the vectors a - b, a - c, and b - c are vectors that point in directions parallel to each of the legs formed by the triangle with these points as its vertices.

If this triangle is to contain a right angle, then exactly one of these pairs of vectors must be orthogonal. In other words, one of the following must be true:

(a - b) • (a - c) = 0

or

(a - b) • (b - c) = 0

or

(a - c) • (b - c) = 0

We have

a - b = (x, x + 1) - (x + 2, x + 3) = (-2, -2)

a - c = (x, x + 1) - (x + 3, 2x + 4) = (-3, -x - 3)

b - c = (x + 2, x + 3) - (x + 3, 2x + 4) = (-1, -x - 1)

Case 1: If (a - b) • (a - c) = 0, then

(-2, -2) • (-3, -x - 3) = (-2)×(-3) + (-2)×(-x - 3) = 2x + 12 = 0 ==> x = -6

which would make a - c = (-3, 3) and b - c = (-1, 5), and their dot product is not zero. Then the triangles vertices are at the points (-6, -5), (-4, -3), and (-3, -8).

Case 2: If (a - b) • (b - c) = 0, then

(-2, -2) • (-1, -x - 1) = (-2)×(-1) + (-2)×(-x - 1) = 2x + 4 = 0 ==> x = -2

which would make a - c = (-3, -1) and b = (-1, 1), and their dot product is also not zero. The vertices are the points (-2, -1), (0, 1), and (1, 0).

Case 3: If (a - c) • (b - c) = 0, then

(-3, -x - 3) • (-1, -x - 1) = (-3)×(-1) + (-x - 3)×(-x - 1) = x ² + 4x + 6 = 0

but the solutions to x here are non-real, so we throw out this case.

So there are two possible values of x that make a right triangle, x = -6 and x = -2.

3 0

3 years ago