# Sarin learns Perimeter, Area and Volume in school part 113 (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 presents the Math Concept, the Math Questions with solutions that teaches in Singapore Primary Schools. You or the kids can acquire the skill of dealing with the Math Modeling, the Math Problem Solving and the 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 Shapes and Ratio.

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

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

Read the posting on Sarin learns ratio in school (Math Concept) to learn about concept of Ratio.

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

Upper primary school mathematics question UPQ526

In the diagram, ∠ ABC = ∠ BDC, AB = 7 cm and AC = 5.4 cm.

1. Prove that triangle ABC is similar to triangle ABD.
2. Calculate the length of AD.

Solution:

Compare the triangle ABC and the triangle ABD,

∠ ABC is common for both triangle

Given ∠ ABC = ∠ BDC

As the sum of the all three inner angles for a triangle is 1800

This mean, BCA = ABD

Hence, the triangle ABC is similar to triangle ABD

Separate the two triangles,

Based on the ratio of the length of the triangles,

AC : AB = AB : AD

5.4 : 7 = 7 : AD

AD = 49/5.4 = 9.074 cm