First step: name the sides according to geometry standards, namely, the sides are named the same lowercase letter as the opposing angle. A revised diagram is shown.
Second step: we need to know the relationships of the trigonometric functions.
cosine(A)=cos(63) = adjacent / hypotenuse = AC/AB .................(1)
sine(A)=sin(63) = opposite / hypotenuse = CB/AB .......................(2)
We're given AB=7, so
using (1)
AC/AB=cos(63)
AC=ABcos(63)=7 cos(63) = 7*0.45399 = 3.17993 = 3.180 (to three dec. figures)
Using (2)
BC/AB=sin(63)
BC=ABsin(63) = 7 sin(63) = 7*0.89101 = 6.237 (to three dec. figures).
All fractions that are less than 1/2 but more than 0.
The inequality is 0>1/2
Each side should increase by 2x (left & right, and up & down) so that to match the condition :
7+2x)(6+2x) = 45
Solving it will give you: 4x² + 26x - 3
OK. These problems are easy if you know the quadratic formula,
and they're impossible if you don't.
Here's the quadratic formula:
When the equation is in the form of Ax² + Bx + C = 0
then x = [ -B plus or minus √(B²-4AC) ] / 2A
I'm sure that formula is in your text or your study notes,
right before these questions. You should cut it out or
copy it, and tape it inside the cover of your notebook.
Then, you'll always have it when you need it, until
you have it memorized and can rattle it off.
The first question says 3x² + 5x + 2 = 0
Is this in the form of Ax² + Bx + C = 0 ?
Yes ! A=3 B=5 C=2
so you can use the quadratic formula to solve it.
x = [ -B plus or minus √(B²-4AC) ] / 2A
= [ -5 plus or minus √(5² - 4·3·2) ] / 2·3
= [ -5 plus or minus √(25 - 24) ] / 6
= [ -5 plus or minus √1 ] / 6
x = -4 / 6 = -2/3
and
x = -6 / 6 = -1 .
_______________________________________
The second question says
4x² + 5x - 1 = 0
Is this in the form of Ax² + Bx + C = 0 ?
Yes it is ! A=4 B=5 C= -1
so you can use the quadratic formula to solve it.
x = [ -B plus or minus √(B²-4AC) ] / 2A
Now, you take it from here.
