Yeah, mostly is has to be negative, but in some cases a is greater than 1 than we do some other operations.
1) The perimeter is the sum of the lengths of the straight edge (the diameter of the semicircle) and the length of the arc of the semicircle.
The circumference of a 4 ft circle is
π*diameter = π*4 ft ≈ 12.566 ft
The semicircle will have a length that is half that, 6.283 ft. When this length is added to the diameter, the perimeter is found to be
Perimeter = 4 ft + 6.283 ft ≈ 10.3 ft.
2) The area of a circle is given by the formula
A = (π/4)d²
For a diameter of 15 inches, the area is
A = (π/4)(15 in)² = 56.25π in²
A ≈ 176.7146 in²
The area of the circle is about 176.71 in².
Step-by-step explanation:





For perpendicular lines, m2 = -1/m1; where m1 is the slope of line 1 and m2 is the slope of line 2.
m1 = (-4 - 2)/(4 - 2) = -6/2 = -3
m2 = -1/-3 = 1/3
Equation of the required line is given by: y - 4 = 1/3 (x - (-1))
y - 4 = 1/3 x + 1/3
y = 1/3 x + 1/3 + 4
y = 1/3 x + 13/3
I believe the answer is 60 degrees I am a little confused by that question though