Find the area of the region colored in orange.
For your final step, use the approximation π = 7 2 2 .
Give your answer to 1 decimal place.
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Exactly the same as this question , I just took my answer from here and substituted the side of the square to get my answer
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Popped up in my problems of the day
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@Hung Woei Neoh – LOL, that's just coincidence
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@Jason Chrysoprase – Exactly. Anyway, I solved it the same way as you XD
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@Hung Woei Neoh – Which one solution is easier to you, mine or the others ?
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@Jason Chrysoprase – I dunno. It depends on how you see the shapes and what theorems or formulas you know
ABCD is a square with sides a. O is the center. It is divided ito 4 equal squares. A quarter of the flower is shown as area OMN. L e t M R ⊥ C D . I n r t . Δ M C R , 2 R M = H y p . M C . ⟹ ∠ M C R = 3 0 o ∵ o f s y m m e t r y , ∠ B C N = 3 0 o . C l e a r l y ∠ N C M = 3 0 o . ∴ Δ M N C i s a − 3 0 o − a . C R = 2 3 a , ∴ M O = 2 3 a − 2 1 a . R e q u i r e d a r e a = 4 ∗ { a r e a C M N } = 4 ∗ { a r e a o f s e c t o r N C M − ( a r e a s o f Δ s M O C a n d N O C ) } = 4 ∗ { π ∗ a 2 ∗ 3 6 0 o 3 0 o − 2 ∗ 2 1 ∗ M O ∗ 2 a = 3 a 2 ( π + 3 − 3 3 . ) a = 7 a n d π = 2 2 / 7 , s u b s t i t u t i n g w e g e t a r e a = 1 5 . 4 6 2 8 . This is the copy of my solution of the problem 4 months ago.
The area of the shaded region is: 3 a 2 ∗ ( 2 2 / 7 + 3 − 3 3 ), where a = 7 . We can draw a square inside the orange area whose side is equal to a 2 − 3 by using Pythagoras's theorem. Hence, the area of the square is a 2 ( 2 − 3 ) . Also, the area between our square and the orange area is: 4 ( t h e a r e a o f t h e f o u r c i r c u l a r s e c t o r s = 4 ( 1 2 a 2 ) ( 7 2 2 -3)).
Thus, total area of the orange part: 7 2 ( 2 − 3 ) + 4 ( 1 2 7 2 ) ( 7 2 2 - 3) = 3 7 2 ( 2 2 / 7 + 3 − 3 3 )= 15.5
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Assume that n = Circle segment area and x + y + n = Circle sector area
x + y = Sector Area − Segment Area
= ( x + y + n ) − n = 3 6 0 3 0 × π × 7 2 − ( 3 6 0 6 0 × π × 7 2 − 4 3 × 7 2 ) = 1 2 4 9 × 7 2 2 − ( 6 4 9 × 7 2 2 − 4 4 9 × 3 ) = 6 7 7 − 3 7 7 + 4 4 9 3
Shaded Area = Square Area − 4 ( x + y ) = 7 2 − 4 ( 6 7 7 − 3 7 7 + 4 4 9 3 ) = 1 5 . 4 6 2 . . . ≈ 1 5 . 5