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3 years ago

Solve the system of equations x+4y=15 2x-y=-15

Mathematics

1 answer:

Lady_Fox [76]3 years ago

7 0

x+4y=15 2x-y=-15

We have to make x neg.

-2(x) + 4y (-2)= -2(15)

-2x-8y=-30

2x-y=-15

-9y= -45

Solve for y

Y=-45/-9

Y = 5

Substitute your y answer into one original equation to find x .

x+4y=15

X+4(5)=15

X+20=15

X=15-20

X= -5

Answer is (-5,5)

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dexar [7]

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A.-4x^2y^4

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2 years ago

Point Y is in the interior of ∠XWZ. Given that WX→ and WZ→ are are opposite rays, and m∠XWY=4(m∠YWZ) is m∠YWZ?.

EleoNora [17]

Answer:

m∠YWZ=36°

Step-by-step explanation:

Opposite rays are two rays that both start from a common point and go off in exactly opposite directions. Because of this the two rays (WX and WZ) form a single straight line through the common endpoint W.

If rays WX and WZ are opposite, then angle XWZ is straight angle. A straight angle always has the measure of 180°.

Point Y is in the interior of ∠XWZ, then angles XWY and EWZ are supplementary angles (together form straight angle XWZ). Supplementary angles always add up to 180°, then

m∠XWY+m∠YWZ=180°

You are given that

m∠XWY=4(m∠YWZ).

Substitute it into the previous equality:

4(m∠YWZ)+m\angle YWZ=180°

5(m∠YWZ)=180°

m∠YWZ=36°

5 0

3 years ago

The perimeter of equilateral triangle ABC is 81/3 centimeters, find the length of the radius and apothem.

MAXImum [283]

There is a typo error, the perimeter of equilateral triangle ABC is 81/√3 centimeters.

Answer:

Radius = OB= 27 cm

Apothem = 13.5 cm

A diagram is attached for reference.

Step-by-step explanation:

Given,

The perimeter of equilateral triangle ABC is 81/√3 centimeters.

Substituting this in the formula of perimeter of equilateral triangle = $3\times\ side$

$3\times\ side$ $=[tex]81\sqrt{3}$

$Side = \frac{81\sqrt{3} }{3} =27\sqrt{3} \ cm$

Thus from the diagram , Side $AB=BC=AC= 27\sqrt{3} \ cm$

We know each angle of an equilateral triangle is 60°.

From the diagram, OB is an angle bisector.

Thus $\angle OBC = 30$ °

Apothem is the line segment from the mid point of any side to the center the equilateral triangle.

Therefore considering ΔOBE, and applying tan function.

$tan\theta =\frac{perpendicular}{base} \\tan\theta=\frac{OE}{BE} \\tan\theta=\frac{OE}{\frac{27\sqrt{3}}{2} } \\tan30\times {\frac{27\sqrt{3} }{2} }= OE\\\frac{1}{\sqrt{3} } \times\frac{27\sqrt{3} }{2} =OE\\$

Thus ,apothem OE= 13.5 cm

Now for radius,

We consider ΔOBE

$cos\theta=\frac{base}{hypotenuse} \\cos30= \frac{BE}{OB} \\Cos30 = \frac{\frac{27\sqrt{3} }{2}}{OB} \\OB= \frac{\frac{27\sqrt{3} }{2}}{cos30} \\OB= \frac{\frac{27\sqrt{3} }{2}}{\frac{\sqrt{3} }{2} } \\OB =27 \ cm$