# Thread: Trignometry minimum & maximum values

1. ## Trignometry minimum & maximum values

How can we get minimum & maximum values of "acosA+bsinB+c".
(I am unable to understand it.could you simplify & magnify the solution & give it to me)

2. Can you use Calculus and does a=A?

3. Originally Posted by rohith14
How can we get minimum & maximum values of "acosA+bsinB+c".
(I am unable to understand it.could you simplify & magnify the solution & give it to me)
$\displaystyle -1 \leq cos A \leq 1$
$\displaystyle -1 \leq sin B \leq 1$

substituting: -1, 0, 1

a(-1) + b(-1) + c = c - a - b
a(-1) + b( 0) + c = c - a
a(-1) + b(+1) + c = c - a + b

a(0) + b(-1) + c = c - b
a(0) + b( 0) + c = c
a(0) + b(+1) + c = c + b

a(+1) + b(-1) + c = c + a - b
a(+1) + b( 0) + c = c + a
a(+1) + b(+1) + c = c + a + b

Those are the maximum & minimum values possible.
IF you know the sign value of a,b,c then you can determine exactly which case applies.

Without knowing the positive/negative magnitudes of a,b,c you cannot give a specific answer.

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4. ## Trignometry maximam & minimum values

we should not use caliculs and A&B are angles the sign may be +ve or -ve

sorry i didn't think in ur way.