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3 years ago

Help me please ): I'm stuck here I don't remember how to do this .----.

Mathematics

1 answer:

inessss [21]3 years ago

8 0

The last number would be 86 , TRUST ME I know these stuff!!

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In a right triangle ABC, CD is an altitude, such that AD=BC. Find AC, if AB=3 cm, and CD= 2 cm.

konstantin123 [22]

Consider right triangle ΔABC with legs AC and BC and hypotenuse AB. Draw the altitude CD.

1. Theorem: The length of each leg of a right triangle is the geometric mean of the length of the hypotenuse and the length of the segment of the hypotenuse adjacent to that leg.

According to this theorem,

$BC^2=BD\cdot AB.$

Let BC=x cm, then AD=BC=x cm and BD=AB-AD=3-x cm. Then

$x^2=(3-x)\cdot 3,\\ \\x^2=9-3x,\\ \\x^2+3x-9=0,\\ \\D=3^2-4\cdot (-9)=9+36=45,\\ \\\sqrt{D}=\sqrt{45}=3\sqrt{5},\\ \\x_1=\dfrac{-3-3\sqrt{5} }{2}0.$

Take positive value x. You get

$AD=BC=\dfrac{-3+3\sqrt{5} }{2}\ cm.$

2. According to the previous theorem,

$AC^2=AD\cdot AB.$

Then

$AC^2=\dfrac{-3+3\sqrt{5} }{2}\cdot 3=\dfrac{-9+9\sqrt{5} }{2},\\ \\AC=\sqrt{\dfrac{-9+9\sqrt{5} }{2}}\ cm.$

Answer: $AC=\sqrt{\dfrac{-9+9\sqrt{5} }{2}}\ cm.$

This solution doesn't need CD=2 cm. Note that if AB=3cm and CD=2cm, then

$CD^2=AD\cdot DB,\\ \\2^2=AD\cdot (3-AD),\\ \\AD^2-3AD+4=0,\\ \\D$

This means that you cannot find solutions of this equation. Then CD≠2 cm.

8 0

3 years ago

Read 2 more answers

Jaylee bought a pair of shoes and are seems to receive some below from the store she's trying to figure out the sales tax rate t

Anna35 [415]

Answer:

28.62*0.057=1.63134

so about 1.63

Hope This Helps!!!

3 0

3 years ago

What is -0.6(r+0.2) = 1.8 ???

lana66690 [7]

Answer:

r = -3.2

Step-by-step explanation:

-0.6(r+0.2) = 1.8

Divide by -.6

-0.6/-.6(r+0.2) = 1.8/-.6

r+.2 = -3

Subtract .2 from each side

r+.2-.2 = -3-.2

r = -3.2

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3 years ago

A kite is a quadrilateral with two pairs of adjacent, congruent sides. The vertex angles are those angles in between the pairs o

ExtremeBDS [4]

Try the answer vertex

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3 years ago

Reptile [31]

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The answer would be: (X,Y) — (x-3, y + 5)

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3 years ago