∆BOC is equilateral, since both OC and OB are radii of the circle with length 4 cm. Then the angle subtended by the minor arc BC has measure 60°. (Note that OA is also a radius.) AB is a diameter of the circle, so the arc AB subtends an angle measuring 180°. This means the minor arc AC measures 120°.
Since ∆BOC is equilateral, its area is √3/4 (4 cm)² = 4√3 cm². The area of the sector containing ∆BOC is 60/360 = 1/6 the total area of the circle, or π/6 (4 cm)² = 8π/3 cm². Then the area of the shaded segment adjacent to ∆BOC is (8π/3 - 4√3) cm².
∆AOC is isosceles, with vertex angle measuring 120°, so the other two angles measure (180° - 120°)/2 = 30°. Using trigonometry, we find
where 
is the length of the altitude originating from vertex O, and so
where 
is the length of the base AC. Hence the area of ∆AOC is 1/2 (2 cm) (4√3 cm) = 4√3 cm². The area of the sector containing ∆AOC is 120/360 = 1/3 of the total area of the circle, or π/3 (4 cm)² = 16π/3 cm². Then the area of the other shaded segment is (16π/3 - 4√3) cm².
So, the total area of the shaded region is
(8π/3 - 4√3) + (16π/3 - 4√3) = (8π - 8√3) cm²
Answer:
1. Dave worked for 34 hours.
2. Perimeter of the rectangle is 172 cm.
Step-by-step explanation:
1. Determination of the hours Dave worked.
Let D represent Dave.
Let M represent Mike.
Let J represent John.
Tota time worked by Dave, Mike and John is 56 hours. This can be written as:
D + M + J = 56 ..... (1)
Dave worked 6 more than 4 times as many hours as Mike. This can written as:
D = 6 + 4M .....(2)
John worked 6 less than 3 times as many hours as Mike. This can be written as:
J = 3M – 6 ........ (3)
Substituting the value of F and J into equation 1, we have:
D + M + J = 56
D = 6 + 4M
J = 3M – 6
6 + 4M + M + 3M – 6 = 56
6 – 6 + 4M + M + 3M = 56
8M = 56
Divide both side by 8
M = 56/8
M = 7
Substitute the value of M into equation (2) to obtain the value of D.
D = 6 + 4M
M = 7
D = 6 + 4(7)
D = 6 + 28
D = 34
Therefore, Dave worked for 34 hours .
2. Determination of the perimeter.
Length (L) = 64 cm
Width (W) = 22 cm
Perimeter (P) =?
P = 2(L + W)
P = 2 (64 + 22)
P = 2 (86)
P = 172 cm
Therefore, the perimeter of the rectangle is 172 cm
9:7 There are 18 girls to 14 boys. 18/14 divide top and bottom by 2 to simplify equals 9:7
Answer:
36
Step-by-step explanation:
x^2 + 12 x = 40
To complete the square, take the coefficient of the x term
12
Divide by 2
12/2 = 6
Square it
6^2 = 36
Add 36 to each side
