NCERT Solutions for Class 4th Maths Chapter 1 Counting angles in a drawing — When Lines Meet
Book page 10 Updated on2026-09-19
Q1.
There are 7 angles in this house drawing. How many angles are there in this boat drawing?
The house drawing from the book, with its 7 angles marked.The boat drawing from the book: two sails on a mast and a hull.
Answer
There are 10 angles in the boat drawing.
Count them corner by corner, the same way the house was counted.
Left sail (a triangle) = 3 angles
Right sail (a triangle) = 3 angles
Hull (a four-sided shape) = 4 angles
Total = 3 + 3 + 4 = 10 angles
The same boat with every angle marked.
Why it happens: An angle is made wherever two lines meet.
So every corner of the picture is one angle — a triangle gives 3 corners and a
four-sided shape gives 4.
Check it yourself: Count the house the same way — roof
triangle 3 + square 4 = 7 angles, exactly as the book says.
Q2.
Mark the angles in the following pictures. a) b) c) d) e)
The five pictures of the Let Us Do activity.
Answer
In each picture find the point where two straight parts meet, and draw a
small arc there.
Picture
Where the angle is
Kind of angle
a) scissors
at the screw, between the two open blades
changes as you open and close them
b) hanger
at the top, between the two slanting arms; also where each arm meets the bar
the top one is obtuse
c) two raised fingers
at the knuckle, between the two fingers
acute
d) see-saw
where the plank rests on the stand
one side acute, the other obtuse
e) slide
between the ladder and the ground, and between the slide and the ground
the ladder makes a right angle; the slide makes an acute angle
Why it happens: Two lines meeting at a point always make
an angle. The wider they open, the bigger the angle — that is why an opening pair of
scissors makes a bigger and bigger angle.