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nignag [31]
2 years ago
13

21. Combine the complex numbers (9+81)-(2+81)+(9 +21)

Mathematics
1 answer:
zhuklara [117]2 years ago
6 0

Answer:

37

Step-by-step explanation:

90-83+30=37

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The base of a pentagonal prism is regular with an apothem of 4 cm. The height of the prism is 16 cm. Find the volume of the pris
Georgia [21]

Answer:

volume ≈ 930 cm³ (nearest cubic cm)

Step-by-step explanation:

The base of the prism which is a pentagon is regular. The apothem which is a line drawn from the center to any side of the pentagon is 4 cm. The height of the prism is 16 cm.

The volume of a prism = Bh

where

B = base area

h = height of the prism

The base of the prism can be divided into 5 congruent triangles.But the base of the triangles is unknown.

The sum of interior angle of a pentagon is 540°. That means each angle is 108° . The triangle divide the angle into 2. Making the 2 base angle as 54° each. The last angle of the triangle at the center is 72°(remember sum of angle in a triangle is 180° which is 54° + 54° + 72° = 180°) .

The angle form the center can be divided by the line of height of the triangles. The angle will then be 36°. Using tangential ratio half of the length of the base of the triangle can be known. Therefore,

tan 36° = opposite/adjacent

tan 36° = opposite/4

opposite = 4 tan 36°

The full base of the triangles = 2(4 tan 36°)

area of each triangle = 1/2 × 2(4 tan 36°) × 4 = 16 tan 36°

Base area of the prism(pentagon) = 5 × 16 tan 36° = 80 tan 36°

Volume of the prism = Bh

where

h = 16 cm

B = 80 tan 36°

volume =  80 tan 36° × 16 = 1280  tan 36° = 1280  × 0.726542528

volume = 929.974435847  cm³

volume ≈ 930 cm³ (nearest cubic cm)

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3 years ago
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2 years ago
A bike with an original price of $90 is discounted 40%. What is the sale price?
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So you do $90 times .40 because 40%=.40 then next you set up your problem

90x.40=36


In total the sales price is $36
5 0
2 years ago
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A projectile is fired from ground level with an initial speed of 550 m/sec and an angle of elevation of 30 degrees. Use that the
Nana76 [90]

Answer:

x (max) = 26760 m

y (max)  = 3859  meters

V = 549.5  m/sec

Step-by-step explanation:

Equations to describe the projectile shot movement are:

a(x)  =  0     V(x)  =  V(₀) *cos α                  x  =  V(₀) *cos α  * t

a(y)  = -g     V(y)  =  V(₀) * sin α  - g*t         y  =   V(₀) * sin α *t  - (1/2)*g*t²

a ) What is the range of the projectile.   α  =  30°

then  sin 30° = 1/2     cos  30° = √3 /2   and     tan 30° = 1/√3

x  maximum occurs when in the equation of trajectory  we make  y  = 0

Then

y  =  x*tan α  -  g*x / 2*V(₀)²*cos²  α

x*tan α  =  g*x /  2* V(₀)²*cos²  α

By subtitution

1/√3    =   9.8* x(max)  / 2* (550)²*0.75

(1/√3) * 453750 / 9.8  = x (max)

x (max) = 453750 / 16.95   meters

x (max) = 26760 m

The maximum height is when V(y) = 0

We compute t in that condition

V(y)  =  0  =  V(₀) * sin α - g*t

t  =   V(₀) * sin α / g       ⇒   t  =  550* (1/2) / 9.8

t  =  28.06 sec

Then  h (max)  =   y(max)  =  V(₀) sin α * t  - 1/2 g* t²

y (max)  =  550* (1/2)*28.06 - (1/2)* 9.8 * (28.06)²

y (max)  =  7717  -  3858  

y (max)  = 3859  meters

What is the speed when the projectile hits the ground

V  =  V(x)  + V (y)    and   t  =  2* 28.06         t  =  56.12 sec

mod V  =√ V(x)²  + V(y)²

V(x)  =  V(₀) cos α    =  550 * √3/2

V(x)  = 475.5  m/sec       V(x)²   =  226338 m²/sec²

V(y) =  550*1/2   -  9.8* 56.12     ⇒  V(y) = 275  -  549.98

V(y) =  - 274.98          V(y) ²   =  

V =  √ 226338 + 75614     ⇒  V = 549.5  m/sec

7 0
3 years ago
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