Let a = 13, b = 14 and c = 15. Then,  s = 1 2 a + b + c=21

 (s- a) = 8, (s - b) = 7 and (s - c) = 6.

Area = s s - a s - b s - c = 21 × 8 × 7 × 6 = 84 sq.cm   

Let original length = x and original breadth = y.

Original area = xy. 

New length = x/2 and New breadth=3y 

New area =  3 2 x y 

Therefore,  Increase in area = New area-original area =  3 2 x y - x y = 1 2 x y 

Therefore,  Increase % =  i n c r e a s e i n a r e a o r i g i n a l a r e a * 100 = 1 2 x y x y * 100 = 50 %

Let the breadth of floor be 'b' m.

Then, length of the floor is 'l = (b + 25)'

Area of the rectangular floor = l x b = (b + 25) × b

According to the question,

(b + 15) (b + 8) = (b + 25) × b

b 2 + 8 b + 15 b + 120 = b 2 + 25 b

2b = 120

b = 60 m.

l = b + 25 = 60 + 25 = 85 m.

Area of the floor = 85 × 60 = 5100 sq.m.

100 cm is read as 102 cm. 

A1 = (100*100)Sq.cm 

A2 = (102*102)Sq.cm

(A2 - A1) = 102 2 - 100 2 = (102 + 100) x (102 - 100) = 404 sq.cm.

2 l + b b = 5 1      => 2l + 2b = 5b     => 3b = 2l 

b=(2/3)l

Then, Area = 216 cm² 

=> l x b = 216     => l x (2/3)l =216 

l = 18 cm.

required area = (area of an equilateral triangle of side 7 cm)- (3 * area of sector with à = 60 degrees and r = 3.5cm)
3 4 * 7 * 7 - 3 * 22 7 * 3 . 5 * 3 . 5 * 60 360 sq cm

= 3 4 * 49 - 11 * 0 . 5 * 3 . 5 sq cm

= 1.967 sq cm

Area of 4 walls = 2(l+b)h
=2(10+7) x 5 = 170 sq m
Area of 2 doors and 3 windows = 2(1x3)+(2x1.5)+2(1x1.5) = 12 sq m
area to be planted = 170 -12 = 158 sq m

Cost of painting = Rs. 158 x 3 = Rs. 474

Area of square = 40 x 40

= 1600 sq.cm

Given that the areas of Square and Rectangle are equal

=> Area of rectangle = 1600 Sq.cm

We know that, Area of rectangle = L x B

Given L = 64 cm

Breadth of rectangle = 1600/64 = 25 cm

Perimeter of the rectangle = 2(L + B) = 2(64+25) = 178 cm.

Let the height of the parallelogram be x. cm. Then, base = (2x) cm.

2 x × x = 72 = > 2 x 2 = 72 = > x = 6