Im so confused! im sure these r the correct answers!! but it keeps saying no! is it really worng or is is the programs error!? (some times hte program does make errors -_-) thxs for the help
Hello S2KrazyWhat you need to know:
- Double-angle formulae. These are the ones you need here:
and
- When the various trig functions are positive. Here's the diagram:
(Remember ACTS starting in QI and going clockwise.)
- and
So for #3, A is in QIII, so only tangent is positive: sine and cosine are both negative. So if (Pythagoras) and .
Using :For # 4, x is in QIV, so only cosine is positive; sine and tangent are negative. So (Pythagoras)
(You can check this out.)For #5, all functions are positive in QI. So (Pythagoras)
(Check my working)Grandad
Hello, S2Krazy!
Sorry, you made errors on all of them . . .
We need the identity: .Let .with in Q3. . Find
We have: .
So:.
. . Pythagorus says: .
Since is in Q3,
. . Hence: .
Therefore: .
Let .with in Q4. . Find
We have: .
So: .
. . Pythagorus says: .
Since is in Q4: .
. . Hence: .
Then: .
Therefore: .
Let .with in Q1. . Find
We have: .
So: .
. . Pythagorus says: .
Hence: .
Then: .
Therefore: .
Edit: Too fast for me, Grandad . . . Nice job, too!
.