Page 321 - Start Up Mathematics_7

Section C

3. Fill in the blanks: 1 M × 5 = 5 M
(a) If two parallel lines are cut by a transversal, each pair of __________ angles are equal in measure.
(b) An __________ angle of a triangle is equal to the sum of its interior opposite angles.
(c) A linear pair is formed by two __________ angles that are supplementary.

(d) A ___________ divides a circle into two congruent parts.
(e) In a right triangle the square of the ___________ is equal to the ___________ of the squares of the
other two sides.

Section D

4. Give one word or sentence for the following: 1 M × 5 = 5 M
(a) If ∆ ABC ≅ ∆ PQR, write the parts of ∆ PQR that correspond to:
(i) ∠A (ii) AC (iii) ∠C

(b) Is it possible to have a triangle with sides of measure 10.2 cm, 5.8 cm and 4.5 cm?
(c) Two angles of a triangle are 30° and 80°. Find the third angle.
(d) What is the difference between the median and the altitude of a triangle?
(e) Find the angle which is equal to its complement.

Section E

5. Find the value of x, y and z in the following figure: 2 M

x
30° 15°
z
y

A
6. ABC is an isosceles triangle in which AB = AC and AD is an altitude. 3 M
(a) State the three pairs of equal parts in ∆ ADB and ∆ ADC.

(b) Is ∆ ADB ≅ ∆ ADC? Why or why not?
(c) Is ∠B = ∠C? Why or why not?
(d) Is BD = CD? Why or why not?
B D C
Project Work

Triangles
A
Draw a scalene ∆ ABC of dimensions 6 cm, 7 cm and 8 cm as
shown in the figure given alongside on a tracing paper and
cut it. 6 cm 7 cm
Using paper folding technique obtain its median AE and
altitude AD. Show it to your teacher and discuss the concept
used. B D E C
8 cm

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