# pre-calc

posted by .

Can someone check my work please?

Convert each polar equation to a rectangular equation. Then determine the graph's slope and y-intercept.
( I'm going to type 'x' instead of theta )
r sin(x- pi/4)=2

r(sin(x- pi/4))=2
r(sinx*cos pi/4 - sin pi/4*cosx)=2
r(sqrt2/2*sin x - sqrt2/2*cos x)=2
sqrt2/2*rsin x - sqrt2/2*rcosx=2
(sqrt2/2*y - sqrt2/2*x=2)^2
1/2(y^2) - 1/2(x^2)= 4
1/2(y^2 - x^2)=4
y^2 - x^2= 8
(y^2= 8 + x^2) sqrt
y= sqrt(8) + x

slope= 1
y-int= sqrt 8

miraculously, you made two major errors that cancelled each other out, and you came up with the right answer.

line 4 can be reduced to √2y - √2x = 4
which convert to y = -x + √8

why are you squaring the equation in line 5???, you had it!!!

When you square an equation you CANNOT just square each term.
Your left side should have contained 3 terms.
Then in line 9 you cannot take the square root of each term!

eg. √(16+9) is not equal to √16 + √9

## Similar Questions

2. ### Calculus

I wanted to confirm that I solved these problems correctly (we had to convert the polar curves to Cartesian equations). 1.rcos(theta)=1 x=1 2.r=2*sin(theta)+2*cos(theta) r^2=2rsin(theta)+2rcos(theta) x^2+y^2=2y+2x (a little unsure …
3. ### pre calc trig check my work please

sin x + cos x -------------- = ? sin x sin x cos x ----- + ----- = sin x sin x cos x/sin x = cot x this is what i got, the problem is we have a match the expression to the equation work sheet and this is not one of the answers. need
4. ### Pre-Calculus

translate this polar equation into a rectangular form: rsin(2theta)=sin(theta) My answer: r2sin(theta)cos(theta)=sin(theta) 2rcos(theta)=1 2x=1 x=1/2 This is the only answer I can get and someone told me it's wrong. Would someone please …
5. ### PRECALCULUS

convert the polar equation to rectangular form. 1.) r sec(theta) = 3 2.) r = 4 cos(theta) - 4 sin(theta) convert from rectangular equation to polar form. 1.) x^2 + (y-1)^2 = 1 2.) (x-1)^2 + (y+4)^2 = 17

convert the polar equation to rectangular form. 1.) r sec(theta) = 3 2.) r = 4 cos(theta) - 4 sin(theta) convert from rectangular equation to polar form. 1.) x^2 + (y-1)^2 = 1 2.) (x-1)^2 + (y+4)^2 = 17