Question

The area of a triangle is 20 cm², and the

Answer 1

Answer:

Heavenly,  we need the forumula for the area of a triangle, do you know it?

Step-by-step explanation:

Area of a triangle is (1/2 ) * B*H

where B = base

H = height

then

A = 1/2* B * H

A is given to be 20

B = b

H = b+4

plug all those into the formula,

20 = (1/2)*b*(b+4)

use your algebra skillz  :P

20 = 1/2 *( $b^{2}$ + 4b)

20*2 = $b^{2}$ + 4b

40 = $b^{2}$ + 4b

0 = $b^{2}$ + 4b-40

rewrite the above so it's in x format

$x^{2}$ + 4x -40 = 0

use the quadratic formula to find  x  , and for our problem, remember that x represents the base,  or b,  but don't mix it up with the b in the quadatic fomula,  with the b of the triangle, which is the base,  they are differnt "b"s   :P

X = (b±$\sqrt{b^{2}-4*a*c }$ ) / 2*a

a = 1

b = 4

c = -40

x = (4±$\sqrt{4^{2}-4*1*(-40) }$  ) /2*1

x = ( 4±$\sqrt{16+160}$ ) / 2

x = (4±$\sqrt{176}$ ) / 2

x = (4±13.266499)/2

x= 2±6.633249

x = 2 + 6.633249 = 8.633

b= 8.633 cm