These NCERT Solutions for Class 7 Maths Chapter 10 Practical Geometry Ex 10.4 Questions and Answers are prepared by our highly skilled subject experts.
NCERT Solutions for Class 7 Maths Chapter 10 Practical Geometry InText Questions
Question 1.
A student attempted to draw a triangle whose rough figure is given here. He drew QR first. Then with Q as centre, he drew an arc of 3 cm and with R as centre, he drew an arc of 2 cm. But he could not get R What is the reason? What property of triangle do you know in connection with this problem?
im
Can such a triangle exist? (Remember the property of triangles ‘The sum of any two sides of a triangle is always greater than the third side’!)
Answer:
Such a triangle does not exist, because a triangle is possible only when the sum of the lengths of any two sides is greater than the third side. But here, 2 cm + 3 cm, i.e. 5 cm < 6 cm.
Question 2.
In ∆ABC if AB = 3 cm, AC = 5 cm and m∠C = 30°. Can we draw this triangle?
Answer:
We may draw AC = 5 cm and ∠C = 30°. CA is one arm of ∠C. But we observe that point B cannot be located uniquely. So, the given data is not sufficient for construction of ∆ABC.
Question 3.
In the example (see Page 201, NCERT Textbook), length of a side and measures of two angles were given. Now study the following problem:
In ∆ABC, if AC = 7 cm, m∠A = 60° and m∠B = 50°, can you draw the triangle? (Angle sum property of a triangle may help you!)
Answer:
We are given the line segment AC. ∠A is given but ∠C is not given. We can determine ∠C using angle-sum property.
∠C = 180° – (∠C + ∠A).
= 180° – (60° + 50°)
= 180° – 110° = 70°
Now, with the help of ∠C, we can construct the triangle.