integration

[valid quartz]

Can I have help with part b

[stiff gorge]

dx/dtheta = 2root2 cos(theta)
if x=2root2 sin(theta) then x^2 = 8sin^2 (theta)
use trig identity sin^2 theta + cos^2 theta = 1

[valid quartz]

See what I did was I just square root the 8sin^2(theta) to give 2root2 sin(theta)

😭😭

I guess you can’t do that

[stiff gorge]

But you have 8-8sin^2(theta) in the square root

[valid quartz]

Yh I just square root it all including sin

[stiff gorge]

Noooooo

[valid quartz]

Without replacing it

😭😭😭

[stiff gorge]

(a+b)^2 ≠ a^2 + b^2

[valid quartz]

I see

Thank you I’ll try do the question now

@stiff gorge

Sorry I don’t get it still

In the third step where’s the sin? Why is it just cos there

[stiff gorge]

sqrt(8-8sin^2(theta)) = sqrt(8(1-sin^2(theta)) = sqrt(8cos^2(theta) = 2sqrt2 cos(theta)

[valid quartz]

I get it now