Question

CLASS 9 MATHEMATICS [HERON’S FORMULA]

Q1] Find the base of an isosceles triangles whose area is 12cm^2 and the length of one of the equal side is 5cm.

Q2] If the perimeter of a rhombus is 20cm and one of the diagonals is 8cm. The area of the rhombus is
(a) 24 sq cm (b) 48 sq cm (c) 50 sq cm (d) 30 sq cm
EXPLAIN

Q3] One of the diagonals of a rhombus is 12cm sides area is 54 sq cm. the perimeter of the rhombus is
(a)72cm (b) 3 root 10 cm (c) 6 root 10 cm (d) 12 root 10 cm
EXPLAIN

PLEASE REPLY SOON. I NEED IT URGENTLY

Answer 1

2) We know ar of rhombus 1/2 diagonal 1 * Diagonal 2
Peri meter = 20
Side = 5 cm ( All sides r equal)
Let longer diagonal be 8 cm
Diagonals bisect at right angles
So side = 5
Half d = 4
Then other d = 3
As they form a right angled Triangle side is hypotenuse d1 is base
(3,4,5 r Pythagorean triplets)
Then d2 = 6 cm

Area=1/2 d1d2
=1/2 6*8
=24 cm

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3) area = 1/2 d1d2
1/2 12 d = 54
d = 9
1/2 d = 4.5
Side = 7.5
( By Pythagoras theorem)
P = 7.5*4 = 30 cm

Answer 2

HELLO FRIEND ,

HERE IS YOUR SOLITION,

Both sides are 5.
The base is x
The area is (1/2)x h=12 
xh=24
The height is one leg of a right triangle, half the base another leg, and the hypotenuse is 5.
This has to be a 3-4-5 right triangle.
The base is 3, but that is the base of half of the isosceles triangle. The whole base is 6.
The height is 4 in any case. 
The area is (1/2)*24=12 cm^2
The height is 4 cm, the base 6cm or 8cm.

I HOPE YOU WILL UNDERSTAND