# Sarin learns Perimeter, Area and Volume in school part 66 (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 from Lower Primary School to Upper Primary School level after reading the postings. This posting is an upper primary school math question on Circle, Triangle and Area.

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

Read also the posting on Sarin learns Shapes and Solids in school (Math Concept) to know about shapes

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

Upper primary school mathematics question UPQ261

The figure belows is making up of one circle of diameter 8cm, two identical semicircles of diameter 4 cm and an isocelete triangle. Find the area of coloured part.

Solution:

Partition the figure to half as the dotted line shown

Both upper and lower parts of the figure are identical

Work on base on one part

When use the semicircle of 8cm diameter substract the triangle of 8cm by 4cm give you the orange part and unwanted yellow part as above

By adding the semicircle of radius 4cm to figure 1and left with the orange portion

Two times the orange portion give the area of the coloured part.

The area of the big semicircle = 4 × 4 × π ÷ 2 = 8π

The area of the small semicircle = 4 × π ÷ 2 = 2π

The area of the top half triangle = 8 × 4 ÷ 2 = 16

The area of half of the orange figure = 8π + 2π – 16 =10π – 16 = 15.4cm2

The area of the orange figure = 2 × 15.4 = 30.80cm2