# Sarin learns Perimeter, Area and Volume in school part 82 (Math Question)

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The blog postings are about the Singapore Math. The readers can learn from the postings about Solving Singapore Primary School Mathematics. The blog presenting the Math Concept, Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids can acquire the skill of dealing with Math Modeling, Math Problem Solving and Problem Sum from Lower Primary School to Upper Primary School level after reading the blog postings. This posting is an upper primary school math question on Perimeter and Area.

You can read posting Sarin learns Perimeter, Area and Volume in school(Math Concept) to learn the concept of perimeter and area.

Challenge yourself with the question before look out for the given solution‼!

Upper primary school mathematics question UPQ358

The figure below is made up of a semicircle with centre O, squares, trapeziums and an equilateral triangle ABC. Given that AD = DB = 11.75 cm and ∠ ABE = 135°,

(a) find the total shaded area of two blue squares.

(b) find the total perimeter of the purple shaded regions.

Solution:

Line DO // Line BE // Line AF and ∠ 1350

∠ OTS = 450  and ∠ OTG = 1350

OT // AB and OT is the radius of the semi-circle

OT = DB = 11.75 cm

Similarly

OS = 11.75cm

Line OS is perpendicular to Line OT

The area of the two blue squares = 11.75 × 11.75 ≈ 138.06 cm2

The perimeter of the purple shaded regoions = 11.75 × 4 + π × 11.75 ≈ 83.91 cm