Page 229 - ICSE Math 7

To construct an isosceles triangle when one of the equal sides and the vertical angle are given

Let’s construct an isosceles DABC with one of the equal sides AB = 6.4 cm and vertical angle A as
30°. To do so, follow the steps given below.
Step 1: Draw a line segment AB of length 6.4 cm. A 6.4 cm B

D
Step 2: Draw ∠DAB = 30° at A.

A 6.4 cm B

C D

Step 3: With A as centre, draw an arc of radius 6.4 cm to cut ray AD at C.
Step 4: Join B and C to get the required isosceles DABC. A 6.4 cm B

To construct a right-angled triangle when its two sides forming the right angle are given
Let’s construct a right-angled DABC whose two sides forming the right angle are 6 cm and 8 cm. To
do so, follow the steps given below.
Step 1: Draw a line segment AB of length 6 cm. A 6 cm B

D

Step 2: Draw ∠DAB = 90° at A.
8 cm

A 6 cm B

D
Step 3: With A as centre, draw an arc of radius 8 cm to intersect ray AD at C. C
Step 4: Join B and C to get the required right-angled triangle. 8 cm

A 6 cm B

To construct a right-angled triangle when one of its sides and hypotenuse are given
Let’s construct a right-angled DABC with one side 4 cm and hypotenuse 5 cm. To do so, follow the
steps given below.
Step 1: Draw a line segment AB of length 4 cm. A 4 cm B

D
Step 2: Draw ∠DAB = 90° at A.

A 4 cm B

D
C
Step 3: With B as centre, draw an arc of radius 5 cm to intersect ray AD at C.
Step 4: Join B and C to get the required right-angled DABC. 5 cm

A 4 cm B

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