easy year 13 question parametric

[stoic thistle]

How do you do part a? You have to make it into a Cartesian equation but how? You use the addition formula for y right but how do you do the rest

[thin fern]

x/5=cost
y=3sintcost
y=3sint(x/5)

[noble current]

when y=0

[crude geyser]

Sin(2t)=0

[stoic thistle]

You have to do Cartesian equation then Equal y to 0 no?

[crude geyser]

Make y = 0 then you get points for t. Sub in the values for t into the x equation to get X coordinate

[noble current]

t=0,pi/2

in this case t=0

cause if you use pi/2

you get x as 0

y as 0

but if you enter 0,

coordinates are (5,0)

[noble current]

no

that is longer and annoying

[stoic thistle]

Thanks

[stoic thistle]

Wouldn’t pi/2 be the upper limit not the bottom limit

[noble current]

it would be 0 on top