Answer:
59.15 in^2
Step-by-step explanation:
Using Heron's formula
semiperimeter , s = 1/2 ( 28.8+18+12) = 29.4
Area = sqrt ( 29.4(29.4-28.8)(29.4-18)(29.4-12) ) = 59.15 in^2
Answer:
1. He added 5 instead of subtracted 5.
2. He should have subtracted 5.
3. 2 2/3
Step-by-step explanation:
3x+5=13
subtract 5 to both sides 3x=8
divide both sides by 3 x=8/3 or 2 2/3
So there are two ways.
First you could solve for y and plug it into the calculator. one equation for y1 and another for y2. Then go 2nd trace and press 5 and then press enter 3 times to find the intersection.
the second way is to solve by hand. I would suggest solve the first equation for y and plug the equation solved for y into the other equation. so y = -3x + 9 and 3x-5y=15. Then you could do 3x - 5(-3x+9) = 15. Finally solve for x and plug in x into both equations to see if you get the same y value.
The answer should be (10/3, -1)
