To tessellate a surface using a regular polygon, the interior angle must be a sub-multiple (i.e. factor) of 360 degrees to cover completely the surface.
For a regular three-sided polygon, the interior angle is (180-360/3)=60 °
Since 6*60=360, so a regular three-sided polygon (equilateral triangle) tessellates.
For a regular four-sided polygon, the interior angle is (180-360/4)=90 °
Since 4*90=360, so a regular four-sided polygon (square) tessellates.
For a regular five-sided polygon, the interior angle is (180-360/5)=108 °
Since 360/108=3.33... (not an integer), so a regular five-sided polygon (pentagon) does NOT tessellate.
For a regular six-sided polygon, the interior angle is (180-360/6)=120 °
Since 3*120=360, so a regular six-sided polygon (hexagon) tessellates.
The speed of wind and speed of plane in still air are 23 and 135
km/h respectively.
<u>Step-by-step explanation:</u>
Let the speed of wind and speed of plane in still air are w and p km/h respectively.
The effective speed on onward journey was
................(1)
The effective speed on return journey was
..............(2)
Adding equation (1) and equation (2) we get,
⇒ 
⇒ 
⇒ 
Putting value of in we get:
⇒
⇒ 
⇒ 
Therefore ,The speed of wind and speed of plane in still air are 23 and 135
km/h respectively.
Answer: 200 adult tickets and 400 student tickets were sold.
Step-by-step explanation:
Let x represent the number of adult tickets that were sold.
Let y represent the number of student tickets that were sold.
Adult tickets to a play cost $1.75 each and student tickets cost $1.25 each. If the income from the play was $850, the expression would be
1.75x + 1.25y = 850- - - - - - - - - -1
Suppose there are twice as many student tickets sold as adult tickets. This is expressed as
y = 2x
Substituting y = 2x into equation 1, it becomes
1.75x + 1.25 × 2x = 850
1.75x + 2.5x = 850
4.25x = 850
x = 850/4.25
x = 200
y = 2x = 2 × 200
y = 400
