Question

answer me the 9and 10 question and iam class 9 this chapter name is lines and Angles please​

Answer 1

Answer:

Q9. lets find the sides first-

7/21*420

7*20

140cm

Second side= 6/21*420

6*20

120cm

Third side = 8/21*420

8*20

160cm.

Answer 2

Answer:

Ans.9 Area=2100√15

Step-by-step explanation:

Perimeter=420

Let the side of the triangle be 7x,6x,8x.

7x + 6x + 8x = 420

21x= 420

X =420/21

X =20

7x = 7× 20 = 140

6x = 6 ×20 = 120

8x =8 × 20= 160

s= (140 + 160 + 120)/2

= 420/2

= 210

Area of triangle= √210(210-140)(210-160)(210-120)

= 210 ×70 ×50×90

= 3×7×10×7×10×3×3×10×5×10

Take the double no.

= 3×7×10×10√3×5

Area = 2100√15

Hope you understand my explanation