Recall that A = 1/2bh.
We are given that h = 4+2b
So, putting it all together:
168 = 1/2 b(4+2b)
168 = 1/2(4b + 2b^2)
168 = 2b + b^2
b^2 + 2b - 168 = 0.
Something that multiplies to -168 and adds to 2? There's a trick to this.
Notice 13^2 = 169. So, it's more than likely in the middle of the two numbers we're trying to find. So let's try 12 and 14. Yep. 12 x 14 = 168. So this factors into (b+14)(b-12) So b = -14 or b =12. Is it possible to have a negative length on a base? No. So 12 must be our answer.
Let's check this. If 12 is our base, then according to our problem, 2*12 + 4 would be our height... or 28. so what is 12 * 28 /2?
196. Check.
Hope this helped!
Isosceles triangle because there are 2 angles that's the same.
I got x=18
3(x-4)-2(3x+4)=4(3-x)+5x+4
3x-12-6x-8=12-4x+5x+4
3x-20=16+x
2x=36x
x=18
Adds 3 each time
first term is 5
an=a1+d(n-1)
d=common difference
a1=first term
an=5+3(n-1)
18th term
a18=5+3(18-1)
a18=5+3(17)
a18=5+51
a18=56
C is answer
