Transcript Homework

7.5 Day 2 Values of Trig
Functions in Radians
RADIANS!
Ex 1) If 0 ≤
QII, find
QII
0.9569
< 2 and tan = – 1.419 in
rounded to 4 decimals
Change calc mode to RADIANS!!!
Find related angle:
tan    1.419
(Positive
for ref )
   tan (1.419)
Keep value in calculator
Don’t round until last step!    0.9569
    .9569  2.1847
1
Speaker & Scribe (with calculator)
- Each person will be given a different trig equation
and asked to find the angle
- You will give your calculator to your partner
- As the “scribe” you are to key in EXACTLY what
the “speaker” tells you to
- When you are done with your equation, you
switch roles
- After both partners have solved for their angles,
the angles should match!
Example 2
Partner A
Partner B
If 0 ≤ < 2 and
csc = – 1.244 in QIII,
find rounded to 4
decimals
If 0 ≤ < 2 and
sec = – 1.681 in QIII,
find rounded to 4
decimals
θ ≈ 4.0753
(Don’t round until last step!)
Example 2
Partner A
Partner B
Find related angle:
0.9338
(Positive for ref
QIII
csc   1.244
1
1
sin   

csc  1.244
1 
1 
   sin 
  0.9338
 1.244 
    0.9338  4.0753
)
0.9337
QIII
sec   1.681
1
1
cos   

sec  1.681
1 
1 
   cos 
  0.9337
 1.681 
    0.9337  4.0753
Finding Errors
Ex 3) The following are 2 incorrect methods of
finding θ when cot θ = 0.6494. Explain (write!) why
each method is wrong and fix it to be correct.
1
1
A)   tan (0.6494)
B)  
tan 1 (0.6494)
–1 should not be in the
tan
1
tan 1 (0.6494) 
tan(0.6494) denominator!
–1
Take tan
Correct:
 1 
  tan 

 0.6494 
1
of reciprocal of cot
Finding Errors
Ex 4) Johnny attempts to solve the following question as
shown. Decide if his work is correct or incorrect and then
justify your answer. If it is incorrect, fix the error.
If 0 ≤
<2
and tan
= –2.590 in QIV, find
Step 1: θ' = tan–1(2.590) ≈ 1.2023
Step 2: θ ≈ π + 1.2023 ≈ 4.3439
2
1.2023
QIV
His work in incorrect.
θ is in QIV
He should have subtracted from 2
θ ≈ 2 – 1.2023 ≈ 5.0809
Homework
#717 Pg. 418 37 – 59 odd