# Sarin learns Shapes and Solids in school part 71 (Math Question)

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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 UPQ581

In the figure, ABCD is a square and EFD is an isosceles triangle. AED = 72º and EFB = 51º. Find EDF.

Solution:

ABCD is a square,

EBF = 900 or right angle

Therefore, EBF is a right-angled triangle,

BEF = 1800 – 900 – 510 = 390

AEB is a straight line,

DEF = 1800 – 720 – 390 = 690

EDF is an isosceles triangle with DF = DE,

DFE = DEF = 690

And,

EDF = 1800 – 690 – 690 = 420