Sarin learns Shapes and Solids in school part 70 (Math Question)


The blog postings are about the Singapore Math. The readers can learn from the postings on 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 learn the skills to deal 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 Angles and Shapes.

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

Read the posting on Sarin learns Lines and Angles (Math concept) to understand the concept of lines and angles.

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

Upper primary school mathematics question UPQ566

The figure below is made up of three triangles. ABC is an equilateral triangle, BCD is a right-angle triangle and DEF is an isosceles triangle. ∠ EFD = 680. Find the sum of ∠ CDE and ∠ABD.




Δ ABC is an equilateral triangle,

∠ BAC = ∠ ACB = ∠ ABC = 600

Δ BCD is right-angle triangle,

∠ BCD is right angle

∠ ACD = 900 + 600 = 1500

ABDC is a 4-sided polygon,

∠ CDB + ∠ ABD = 3600 – 1500 – 600 = 1500

Δ DFE is an isosceles triangle, DF = DE,

∠ EFD = ∠ FED = 680

∠ BDE = 1800 – 680 – 680 = 440

∠ CDE + ∠ ABD = 440 + 1500 = 1940

 More Questions on Lines, Shapes and Angles. Click here….


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