Hey
everyone this is Rajvir, I am going to blog about what we learned on March 15,
2012.
We
learned that there are total 6 Identities;
luckily we don’t have to remember them, because they are on our formula sheet.
Basic sum Identities:
Basic difference
identities:
We also learned:
Note: Undefined values will
still occur when the denominator equals to zero.
Example:
1-sin^2(a + B) = cos^2 (a + B)
Basically, we are using these identities
to solve different equations.
Example:
Find
the exact value
of the following using the appropriate formulas
Sin7π
12
Step 1: first we have to write
this expression using a grouping of special triangles that we learnt about in the
very beginning π/3, π/6, and π/4. (VERY IMPORTANT)
Sin7π
= ( 4π + 3π
)
12 12 12
Step 2: Simplify
a B
= ( π + π
)
3 4
Note: Don’t forget to
label which is Alpha and Beta.
Step 3: Plug it in the Sin formula,
because we are finding exact value for Sin 7π
12
= Sin πCosπ + Cos πCosπ
3 4 4 3
Step 4: Using your special
triangles find the exact value of each. (SOH CAH TOA)
= ( √3 ) ( 1 ) +
( 1 )
( 1 )
2 √3 2 √2
= √3 + 1
2√2 2√2
= √3 + 1
2√2
This is how you
solve for exact value of sin. As well as solving
for Cos and Tan involves the same steps. But the difference is that you’re
using a different formula.
In addition, if you
are still confused about the whole concept I suggest that you watch this video
on Sum and Difference identities.
Hope this was
helpful, and that you learned a lot J
No comments:
Post a Comment