NCERT Solutions for Class 5th Maths Chapter 10 Making designs from squares and equilateral triangles — Let Us Do
Book page 139 Updated on2026-09-19
Q1.
Cut out squares and equilateral triangles with the same side length. These are provided at the end of the book. Make different symmetrical designs by using these two shapes.Squares and equilateral triangles with the same side length — the cut-outs given at the end of the book.
Answer
Arrange the shapes evenly round one centre point. If every arm of your design is the same, the design will be symmetrical.
Take the cut-outs from the sheets at the end of the book. Both shapes have the same side length, so any side of a square fits exactly along any side of a triangle.
Two designs made from one square and some triangles.
How to make a symmetrical design:
Put one square in the middle of your page.
Stick one triangle on the top edge of the square, pointing outwards.
Do the same on the right edge, the bottom edge and the left edge. You now have a four-pointed star.
Test it by turning. Turn the page a quarter of the way round — the star looks the same.
Test it by folding. Fold it side to side, top to bottom, and along both slanting lines — all four folds match.
Now change it — put triangles on only the top and bottom edges. This new design looks the same after a 1/2 turn and folds along 2 lines.
Sample answer: I made three designs. Design 1: a square with a triangle on each of its four sides — it looks the same after every 1/4 turn and has 4 lines of symmetry. Design 2: a square with triangles only on the top and bottom — it looks the same after a 1/2 turn and has 2 lines of symmetry. Design 3: four squares in a row with one triangle at each end — it has 1 line of symmetry and looks the same after a 1/2 turn.
The rule you are practising: Put the same thing at every arm and the design will have rotational symmetry. Make the two sides of every arm alike and it will have lines of symmetry as well.