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Ch5.1A – Using Fundamental IdentitiesReciprocal Identities
Quotient Identities
Pythagorean Identities
sin2u + cos2u = 11 + tan2u = sec2u1 + cot2u = csc2u
uu
uu
uu
cot
1tan
sec
1cos
csc
1sin
sin
coscot
cos
sintan
u
uu
u
uu
Cofunction Identities
Even/Odd IdentitiesEven Odd
cos(–u) = cos(u) sin(–u) = –cos(u)sec(–u) = sec(u) tan(–u) = –tan(u)
cot(–u) = –cot(u)csc(–u) = –csc(u)
uuuu
uuuu
uuuu
sec2
csc csc2
sec
tan2
cot cot2
tan
sin2
cos cos2
sin
Ex1) find all six trigs.
Ex2) Simplify: sinx.cos2x – sinx
,0tan and 2
3sec uu
Ex3) Use ur calc to determine if the following are identities:
a) cos3x = 4cos3x – 3cosx
b) cos3x = sin(3x – )
Ex4) Verify by hand:
Ch5.1A p414 19 – 43odd
2
cscsin
cos
cos1
sin
Ch5.1A p414 19 – 43odd Do 19,21,29,31,37,39,41 in class
Ch5.1A p414 19 – 43odd Do 19,21,29,31,37,39,41 in class
Ch5.1A p414 19 – 43odd Do 19,21,29,31,37,39,41 in class
Ch5.1A p414 19 – 43odd Do 19,21,29,31,37,39,41 in class
Ch5.1B – More IdentitiesEx5) Factor:
a) sec2θ – 1 b) 4tan2θ + tanθ – 3
Ex6) Factor: csc2x – cotx – 3
Ex7) Simplify: sint + cott.cost
Ex8) Rewrite not as a fractionxsin1
1
Ex9) If x = 2tanθ, use substitution to express
as a trig function. (0 < θ < π/2)
Ch5.1B p414 45-63odd,71-75odd
24 x
Ch5.1B p414 45-63odd,71-75odd
Ch5.1B p414 45-63odd,71-75odd
Ch5.1B p414 45-63odd,71-75odd
Ch5.1B p414 45-63odd,71-75odd
Ch5.1B p414 45-63odd,71-75odd
Ch5.1C p414 20 – 62 even
Ch5.1C p414 20 – 62 even
Ch5.1C p414 20 – 62 even
Ch5.1C p414 20 – 62 even
Ch5.1C p414 20 – 62 even
Ch5.1C p414 20 – 62 even
Ch5.1C p414 20 – 62 even
Ch5.1C p414 20 – 62 even
Ch5.2A – Verifying Trig Identities
Guidelines: 1. Work one side at a time, usually the most complicated 1st. 2. Look to: - Factor
- Add fractions
- Square a binomial
- Get a monomial denominator 3. Use fundamental identities 4. Head toward sine and cosine
5. But try SOMETHING!
Ex1) Verify:
22
2
sinsec
1sec
Ex2) Verify:
2sec2sin1
1
sin1
1
Ex3) Verify: (tan2x + 1)(cos2x – 1) = –tan2x
Ex4) Verify: tanx + cotx = secx.cscx
HW#25) Verify:
Ch5.2A p421 1 – 10 all
tansec
)sin(1
)cos(
Ch5.2A p421 1 – 10 all
Ch5.2A p421 1 – 10 all
Ch5.2B – More Verifying Trig ID’sEx5) Verify:
y
yyy
sin1
costansec
Ex6) Verify:
sin
sin1
csc1
cot2
Ex7) Verify: tan4x = tan2x.sec2x – tan2x
Verify: sin3x.cos4x = (cos4x – cos6x).sinx
HW#46) Verify:
Ch5.2B p421 21 – 39 odd
cot
1csc
1csc
cot
Ch5.2B p421 21 – 39 odd
Ch5.2B p421 21 – 39 odd
Ch5.2B p421 21 – 39 odd
Ch5.2B p421 21 – 39 odd
Ch5.2C p422 40-48all
Ch5.3A – Solving Trig Functions
Ex1) Solve: 2sinx – 1 = 0
Ex2) Solve: xx sin2sin
Ex3) Solve: 3tan2x – 1 = 0
Ex4) Solve: cotx.cos2x = 2cotx
Ex5) Solve: 2sin2x – sinx – 1 = 0 over [0,2π]
Ex6) Solve: 2sin2x + 3cosx – 3 = 0
Ch5.3A p431 11 – 29odd,60
Ch5.3A p431 11 – 29odd,60
Ch5.3A p431 11 – 29odd,60
Ch5.3B – Solving Trig Functions cont
HW#18) Solve: tan23x = 3
#24) Solve: cos2x.(2cosx + 1) = 0
#35) Solve:
#37) Solve:
Ch5.3B p432 12 – 22even, 31 – 37odd
2
2
2cos
x
0cos1
cos1
x
x
Ch5.3B p432 12 – 22even, 31 – 37odd
Ch5.3B p432 12 – 22even, 31 – 37odd
Ch5.4A – Sum and Difference Formulas
sin(u + v) = sinu.cosv + cosu.sinv sin(u – v) = sinu.cosv – cosu.sinv
cos(u + v) = cosu.cosv – sinu.sinv cos(u – v) = cosu.cosv + sinu.sinv
Ex1) Find the exact value of cos75˚.
tantan1
tantan)tan(
tantan1
tantan)tan(
vu
vuvu
vu
vuvu
sin(u + v) = sinu.cosv + cosu.sinv sin(u – v) = sinu.cosv – cosu.sinv cos(u + v) = cosu.cosv – sinu.sinv cos(u – v) = cosu.cosv + sinu.sinv
Ex2) Find the exact value of , given that
tantan1
tantan)tan(
tantan1
tantan)tan(
vu
vuvu
vu
vuvu
12sin
4312
sin(u + v) = sinu.cosv + cosu.sinv sin(u – v) = sinu.cosv – cosu.sinv cos(u + v) = cosu.cosv – sinu.sinv cos(u – v) = cosu.cosv + sinu.sinv
Ex3) Find the exact value of sin42˚.cos12˚ – cos42˚.sin12˚
tantan1
tantan)tan(
tantan1
tantan)tan(
vu
vuvu
vu
vuvu
sin(u + v) = sinu.cosv + cosu.sinv sin(u – v) = sinu.cosv – cosu.sinv cos(u + v) = cosu.cosv – sinu.sinv cos(u – v) = cosu.cosv + sinu.sinv
Ex4) Prove the cofunction identity
tantan1
tantan)tan(
tantan1
tantan)tan(
vu
vuvu
vu
vuvu
xx sin2
cos
sin(u + v) = sinu.cosv + cosu.sinv sin(u – v) = sinu.cosv – cosu.sinv cos(u + v) = cosu.cosv – sinu.sinv cos(u – v) = cosu.cosv + sinu.sinv
Ex5) Simplify tan(θ + 3π)
tantan1
tantan)tan(
tantan1
tantan)tan(
vu
vuvu
vu
vuvu
Ex6) Solve
Ch5.4A p440 7 – 25odd (7-sin,9-cos,11-sin,13-cos,15-tan)
14
sin4
sin
xx
Ch5.4A p440 7 – 25odd (7-sin,9-cos,11-sin,13-cos,15-tan)
Ch5.4A p440 7 – 25odd (7-sin,9-cos,11-sin,13-cos,15-tan)
Ch5.4A p440 7 – 25odd (7-sin,9-cos,11-sin,13-cos,15-tan)
Ch5.4B – Sum and Difference Formulas cont
sin(u + v) = sinu.cosv + cosu.sinv sin(u – v) = sinu.cosv – cosu.sinv cos(u + v) = cosu.cosv – sinu.sinv cos(u – v) = cosu.cosv + sinu.sinv
HW#12) Solve: tan255˚.
tantan1
tantan)tan(
tantan1
tantan)tan(
vu
vuvu
vu
vuvu
sin(u + v) = sinu.cosv + cosu.sinv sin(u – v) = sinu.cosv – cosu.sinv cos(u + v) = cosu.cosv – sinu.sinv cos(u – v) = cosu.cosv + sinu.sinv
HW#14) Solve:
12
7sin
sin(u + v) = sinu.cosv + cosu.sinv sin(u – v) = sinu.cosv – cosu.sinv cos(u + v) = cosu.cosv – sinu.sinv cos(u – v) = cosu.cosv + sinu.sinv
HW#32) Prove: sin(x+π).sin(x–π) = sin2x
sin(u + v) = sinu.cosv + cosu.sinv sin(u – v) = sinu.cosv – cosu.sinv cos(u + v) = cosu.cosv – sinu.sinv cos(u – v) = cosu.cosv + sinu.sinv
HW#44) Prove: cos(x+y) + cos(x–y) = 2cosx.cosy
Ch5.4B p440 8 – 26 even, 32,44 (8-sin,10-cos,12-tan,14-sin,16-cos)
Ch5.4B p440 8 – 26 even, 32,44 (8-sin,10-cos,12-tan,14-sin,16-cos)
Ch5.4B p440 8 – 26 even, 32,44 (8-sin,10-cos,12-tan,14-sin,16-cos)
Ch5.5A – Multiple Angle Formulas
sin(2u) = 2sinu.cosu cos(2u) = cos2u – sin2u
or = 2cos2u – 1 or = 1 – 2sin2u
Ex1) Find all the solutions of: 2cosx + sin2x = 0
tan1
tan2)2tan(
2 u
uu
sin(2u) = 2sinu.cosu cos(2u) = cos2u – sin2u
or = 2cos2u – 1 or = 1 – 2sin2u
Ex2) Find sin2θ, cos2θ, and tan2θ,
given
tan1
tan2)2tan(
2 u
uu
22
3for
13
5cos
sin(2u) = 2sinu.cosu cos(2u) = cos2u – sin2u
or = 2cos2u – 1 or = 1 – 2sin2u
Ex3) Express sin3x in terms of sinx.
Ch5.5A p451 1 – 25odd, not 15Quiz tomorrow on Sum/Diff/Double Angle Formulas
Ch5.5A p451 1 – 25odd, not 15Quiz tomorrow on Sum/Diff/Double Angle Formulas
Ch5.5A p451 1 – 25odd, not 15Quiz today on Sum/Diff/Double Angle Formulas
Ch5.5A p451 1 – 25odd, not 15Quiz today on Sum/Diff/Double Angle Formulas
Ch5.5A p451 1 – 25odd, not 15Quiz today on Sum/Diff/Double Angle Formulas
Ch5.4,5.5 Quiz Name____________
Form A Form B1. sin(u + v) = 1. cos2θ =2. cos(u + v) = 2. tan2θ =3. sin(u – v) = 3. sin2θ=4. cos(u – v) = 4. cos(u + v) =5. tan(u – v) = 5. cos(u – v) =6. sin2θ= 6. sin(u + v) =7. tan2θ = 7. sin(u – v) =8. cos2θ = 8. tan(u – v) =
Ch5.5B – Multiple Angle Formulas cont
Power Reducing Formulas:
Half Angle Formulas
HW#29) Simplify: sin2x.cos2x
u
uu
uu
uu
2cos1
2cos1 tan
2
2cos1cos
2
2cos1sin 222
cos1
sinor
sin
cos1
2tan
2
cos1
2cos
2
cos1
2sin
u
u
u
uu
uuuu
Power Reducing Formulas:
Half Angle Formulas
HW#28) Simplify: sin4x
u
uu
uu
uu
2cos1
2cos1 tan
2
2cos1cos
2
2cos1sin 222
cos1
sinor
sin
cos1
2tan
2
cos1
2cos
2
cos1
2sin
u
u
u
uu
uuuu
Power Reducing Formulas:
Half Angle Formulas
HW#33) Simplify:
5θ
12
u
uu
uu
uu
2cos1
2cos1 tan
2
2cos1cos
2
2cos1sin 222
cos1
sinor
sin
cos1
2tan
2
cos1
2cos
2
cos1
2sin
u
u
u
uu
uuuu
2cos
Power Reducing Formulas:
Half Angle Formulas
HW#37) Simplify:
5θ
12
u
uu
uu
uu
2cos1
2cos1 tan
2
2cos1cos
2
2cos1sin 222
cos1
sinor
sin
cos1
2tan
2
cos1
2cos
2
cos1
2sin
u
u
u
uu
uuuu
2csc
Power Reducing Formulas:
Half Angle Formulas
HW#39) Simplify: sin105˚
u
uu
uu
uu
2cos1
2cos1 tan
2
2cos1cos
2
2cos1sin 222
cos1
sinor
sin
cos1
2tan
2
cos1
2cos
2
cos1
2sin
u
u
u
uu
uuuu
Power Reducing Formulas:
Half Angle Formulas
HW#43) Simplify:
Ch5.5B p452 27,28,29,33,34,35,37,39,40,41,43,44,45
u
uu
uu
uu
2cos1
2cos1 tan
2
2cos1cos
2
2cos1sin 222
cos1
sinor
sin
cos1
2tan
2
cos1
2cos
2
cos1
2sin
u
u
u
uu
uuuu
8csc
Ch5.5B p452 27,28,29,33,34,35,37,39,40,41,43,44,45
Ch5.5B p452 27,28,29,33,34,35,37,39,40,41,43,44,45
Ch5 Rev p455 1 – 49 eoo, + 31
Ch5 Rev p455 1 – 49 eoo, + 31
Ch5 Rev p455 1 – 49 eoo, + 31
Ch5 Rev p455 1 – 49 eoo, + 31
Ch5 Rev p455 1 – 49 eoo, + 31
Ch5 Rev p455 1 – 49 eoo, + 31
Ch5 Rev p455 1 – 49 eoo, + 31
Ch5 Rev p455 1 – 49 eoo, + 31