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motikmotik
3 years ago
9

Find the angle between the following pairs of lines x^2+6xy +9y^2-4x +12y-5 =0​

Mathematics
1 answer:
wlad13 [49]3 years ago
3 0

Answer:

x

2

+6xy+9y

2

+4x+12y−5=0

Step-by-step explanation:

x

2

+6xy+9y

2

+4x+12y−5=0

Comparing the equation with the general equation of second degree gives

a=1,b=9,h=3,g=2,f=6,c=−5

Angle between a pair of straight lines that is tanθ=

∣

∣

∣

∣

∣

∣

​

 

a+b

2

h

2

−ab

​

​

 

∣

∣

∣

∣

∣

∣

​

tanθ=

∣

∣

∣

∣

∣

​

 

1+9

2

9−1×9

​

​

 

∣

∣

∣

∣

∣

​

=

9

0

​

tanθ=0

⇒θ=tan

−

(0)=0

∘

Angle between the pair of straight lines is zero therefore the lines are parallel.

Hence proved

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A garden is shaped in the form of a regular heptagon (seven-sided), MNSRQPO. A circle with center T and radius 25m circumscribes
Alenkinab [10]

The relationship between the sides MN, MS, and MQ in the given regular heptagon is \dfrac{1}{MN} = \dfrac{1}{MS} + \dfrac{1}{MQ}

The area to be planted with flowers is approximately <u>923.558 m²</u>

The reason the above value is correct is as follows;

The known parameters of the garden are;

The radius of the circle that circumscribes the heptagon, r = 25 m

The area left for the children playground = ΔMSQ

Required;

The area of the garden planted with flowers

Solution:

The area of an heptagon, is;

A = \dfrac{7}{4} \cdot a^2 \cdot  cot \left (\dfrac{180 ^{\circ}}{7} \right )

The interior angle of an heptagon = 128.571°

The length of a side, S, is given as follows;

\dfrac{s}{sin(180 - 128.571)} = \dfrac{25}{sin \left(\dfrac{128.571}{2} \right)}

s = \dfrac{25}{sin \left(\dfrac{128.571}{2} \right)} \times sin(180 - 128.571) \approx 21.69

The \ apothem \ a = 25 \times sin \left ( \dfrac{128.571}{2} \right) \approx 22.52

The area of the heptagon MNSRQPO is therefore;

A = \dfrac{7}{4} \times 22.52^2 \times cot \left (\dfrac{180 ^{\circ}}{7} \right ) \approx 1,842.94

MS = \sqrt{(21.69^2 + 21.69^2 - 2 \times  21.69 \times21.69\times cos(128.571^{\circ})) \approx 43.08

By sine rule, we have

\dfrac{21.69}{sin(\angle NSM)} = \dfrac{43.08}{sin(128.571 ^{\circ})}

sin(\angle NSM) =\dfrac{21.69}{43.08} \times sin(128.571 ^{\circ})

\angle NSM = arcsin \left(\dfrac{21.69}{43.08} \times sin(128.571 ^{\circ}) \right) \approx 23.18^{\circ}

∠MSQ = 128.571 - 2*23.18 = 82.211

The area of triangle, MSQ, is given as follows;

Area \ of \Delta MSQ = \dfrac{1}{2}  \times  43.08^2 \times sin(82.211^{\circ}) \approx 919.382^{\circ}

The area of the of the garden plated with flowers, A_{req}, is given as follows;

A_{req} = Area of heptagon MNSRQPO - Area of triangle ΔMSQ

Therefore;

A_{req}= 1,842.94 - 919.382 ≈ 923.558

The area of the of the garden plated with flowers, A_{req} ≈ <u>923.558 m²</u>

Learn more about figures circumscribed by a circle here:

brainly.com/question/16478185

6 0
3 years ago
I need help on this question and answering it
Contact [7]

Answer:

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the shadow to the object would be a 4:5 ratio

since the shadow of the flagpole is 60 ft,

4x=60 so x would =15

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6 0
3 years ago
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Initially 100 milligrams of a radioactive substance was present. After 6 hours the mass had decreased by 2%. If the rate of deca
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Shalnov [3]
<span> Answer: 90° degrees </span>
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47^2 = 2209

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