help SHM :( (2 Viewers)

[hollyy.]

do we actually have to remember like each transformation.. or will they always specify in an exam to which form they want you to change it to?

just remember
sin at front = sin in transformation
minus in middle = minus in transformation

etc

its all coming back lol.

 

[QuLiT]

i personally don't remmeber the formula, i look at which one will be more useful for the later parts and work it out to that

 

[u-borat]

lol i cbb learning the shorter way so i'm still using what i was taught in year 11; expanding rcos(x+@) or what not, then equating the nonexistent terms with the coefficient and dividing to get tan and squaring to get cos and sin^2.

slow.

 

[QuLiT]

wow>.> i never learnt it like that haha

 

[hollyy.]

lol i cbb learning the shorter way so i'm still using what i was taught in year 11; expanding rcos(x+@) or what not, then equating the nonexistent terms with the coefficient and dividing to get tan and squaring to get cos and sin^2.

slow.

i remember now
thats how i was taught
cause our teacher thinks formulas clutter our brains.

 

[SkimDawg]

here:
Transformations (equations involving the sum of sin and cos / axillary angle method)

• asinx + bcosx = rsin(x+α)
• asinx - bcosx = rsin(x-α)
• acosx - bsinx = rcos(x+α)
• acosx + bsinx = rcos(x-α)

Where:

• r = √(a² + b²)
• α is in the first quadrant such that tanα = b/a

taken from the maths formula wiki thing

Yeah I had to teach my teacher this method lol, he didnt know it.

 

[QuLiT]

haha >.>

 

[daniellekho]

yes the R method! of course..haha thats wat my teacher calls it too