Yxcas's answer to Kc's Primary 6 Maths Geometry Singapore question.

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Yxcas
Yxcas's answer
184 answers (A Helpful Person)
1st
View it as total length is made up of 9 smaller rectangles (blue) and 10 triangles (yellow).

(Two ends view as triangle makes no difference to the length as we are still considering its base length/the unfolded part of the triangle)

Given info:
4 rectangles + 5 triangles = 43cm
1 rectangle + 2 triangles = 13cm

Derived:
3 rectangles + 3 triangles = 43 - 13 = 30cm
1 rectangle + 1 triangle = 30 / 3 = 10cm
5 rectangles + 5 triangles = 10 x 5 = 50cm

Total length of paper =
9 rectangles + 10 triangles = 43 + 50 = 93cm