handsome+JZ's answer to Sarah's Primary 6 Maths Data Analysis Singapore question.
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You need to know the method to find the area of a sector . Wish it helps .
Date Posted:
4 years ago
The area of the equilateral triangle is incorrect. It's height isn't 9cm. If you correctly used Pythagoras' theorem you will get 7.79cm (3s.f) instead.
The final answer ended up being correct because the total area calculated equalled the area of two equivalent sectors, and the area of 1 sector was correctly calculated in your first step.
The final answer ended up being correct because the total area calculated equalled the area of two equivalent sectors, and the area of 1 sector was correctly calculated in your first step.
Alternative method :
Shift the bottom curved segment and join it to the top of the left equilateral triangle.
Since all angles in an equilateral triangle are 60° each, the two combined angles of the two triangles (from the bottom left side of the left triangle to the bottom right side of the right triangle is 120°)
A full circle is considered to have an angle of 360°.
Since 120° ÷ 360° = ⅓, the shaded area is ⅓ of a full circle. So its area is also ⅓ of a full circle.
⅓ x 3.14 x 9 x 9 = 84.78
Shift the bottom curved segment and join it to the top of the left equilateral triangle.
Since all angles in an equilateral triangle are 60° each, the two combined angles of the two triangles (from the bottom left side of the left triangle to the bottom right side of the right triangle is 120°)
A full circle is considered to have an angle of 360°.
Since 120° ÷ 360° = ⅓, the shaded area is ⅓ of a full circle. So its area is also ⅓ of a full circle.
⅓ x 3.14 x 9 x 9 = 84.78
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