Answer:
Look below
Step-by-step explanation:
(a) The area of a triangle is:
[tex]A=\frac{1}{2}bh[/tex]
The height of this triangle is h and it's base is 4+h so...
[tex]A=\frac{1}{2}*[h*(h+4)][/tex]
[tex]A=\frac{1}{2}*(h^2+4h)\\A=\frac{h^2}{2}+2h[/tex]
(b) If the height is 8 cm, then the base is 4+8 which is 12 cm so...
[tex]A=\frac{1}{2}*8*12=4*12=48 \ cm^2[/tex]
