B) A square room is 12 m long and 5 m high. (i) Find the area of its floor and ceiling.
(ii) Find the area of its 4 walls.
(iii) Find the area of the room including floor and ceili
c) The area of 4 walls with two windows and a door is 20
and the door is 6 m², find the area of the walls excludin
3. a)
The area of 4 walls and ceiling of a room is 140 m². Find
and ceiling at Rs 35 per sq. metre.
b) If the cost of plastering 4 walls of a room at Rs 45 per
area of the 4 walls of the room.
Creative section
A room is 10 m long 8 m wide and 5 m high. Find the

4

step-by-step explanation:

im pretty sure it's 4 beacsue 8/2 equals 4

the value of x is 9 ⇒ answer b

step-by-step explanation:

* we can solve this problem using cosine and sine rule

- in δ abc

∵ ab = 36 , bc = 28 , ac = 16

- lets find the measure of angle b using the cosine rule

∵ cos b = [ab² + bc² - ac²]/2(ab)(bc)

∴ cos b = [36² + 28² - 16²]/2(36)(28)

∴ cos b = 19/21

∴ m∠b = cos^-1(19/21) ≅ 25°

- lets find the measure of angle a using the sine rule

∵ sina/bc = sinb/ac = sinc/ab

∴ sina/28 = sin25°/16 ⇒ by using cross multiplication

∴ sina = 28 × sin25°/16

∴ sina = 0.7396

∴ m∠a = sin^-1(0.7396) ≅ 48°

- from the figure m∠abd = m∠dbc

∵ m∠abc = 25°

∴ m∠abd = 25°/2 = 12.5°

- in δabd

∵ m∠a = 48° , m∠abd = 12.5°

∵ the sum of the measures of the interior angles of any δ is 180°

∴ m∠adb = 180° - (48° + 12.5°) = 119.5°

∵ ab = 36

∵ ad = x

- use the sine rule to find x

∵ sin∠adb/ab = sin∠abd/x

∴ sin119.5°/36 = sin12.5°/x ⇒ by using cross multiplication

∴ x = 36 × sin12.5°/sin119.5° = 8.95 ≅ 9

* the value of x is 9