The circumference of a circle of radius 
is
So, in your case, the circumference is
The circumference is actually the length of the "perimeter", so the answer to questions 1 and 2 looks the same actually
Sec^2 x - 1 = tan^2x
Proof:
Sec^2x = 1+ tan^2x
1/cos^2x = 1 + sin^2x/cos^2x
<span>1/cos^2x - sin^2x/cos^2x = 1
</span>Using common denominator:
(1-sin^2x)/cos^2x = 1
sin^2x + cos^2 x = 1
cos^2 x = 1 - sin^2x
Substituting :
cos^2x/<span>cos^2x = 1
</span>1 = 1
Left hand side = right hand side
The answer for your question is B. 5
A number is rational if it can be written in form a/b where a and b are integers and b is not equal to 0
integers are like -4,-3,-2,-1,0,1,2,3,4, etc
so
√20=2√5 which is irrational because we can't write it as a fraciton with only integers
also a rational number multilied by an irratinonal number=irrtaional
we know that the square root of any prime number will be irrational and 5 is prime so 2 times √5=rational times irrational=irrational
√20 is irrational
(0, 5), (1, 1 ), ( - 1, 9 )
to test the points substitute the x-coordinate into the equation and if the value is equal to the y- coordinate then it is an ordered pair
(0, 5 ) → y = 0 + 5 = 5 ← ordered pair
(1, 1 ) → y = - 4 + 5 = 1 ← ordered pair
(- 1, 9 ) → y = 4 + 5 = 9 ← ordered pair
( - 1, - 1 ) → y = 4 + 5 = 9 ← not an ordered pair
( - 1, - 9 ) → y = 4 + 5 = 9 ← not an ordered pair
(1, - 1 ) → y = - 4 + 5 = 1 ← not an ordered pair
(- 1, 1 ) → y = 4 + 5 = 9 ← not an ordered pair
