Triangles/Sine/Cosine?

[rain wren]

,rotate

[rain wren]

cosine rule

a²=b²+c²-2bc*cosA

(2x+1)²=(x+2)²+(3x-3)²-2(x+2)(3x-3)cos60

cos 60 in degrees is a 1/2

[gloomy pond]

Thats for which one b? Can u do a please. Thank you so much btw

[rain wren]

what I just did was for A

for b

Once you've found x

and it must be a value which means your side lengths stay positive

you can use the sine rule

to find the angle

[gloomy pond]

Wait, I know I look dumb. But how does this link to the quadratic?

[shut leaf]

the sides

[rain wren]

your side lengths are in terms of x

I can use the cosine rule

to create an expression in x

and solve it

[shut leaf]

think you leaving cos60 at the end instead of 1/2 threw him off since you just have to use foil from there onwards and collect terms

[shut leaf]

watch this video if you still don’t understand where that has came from

https://youtu.be/q7fG4qQljgo?feature=shared

it’s only 4mins long

[gloomy pond]

Okay I will watch it rn. Tysm guys