Simplify: cos(²⁵π/₉)cos(¹⁰π/₉) + sin(²⁵π/₉)sin(¹⁰π/₉)

🌈 Applying Trig Identities ⭐️
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P15

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🔴 If csc𝜃 = 25/7 & 90º＜𝜃＜180º, find csc(2𝜃).

P16

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🟡 If sin𝜃 = -3/5 & 3π/2＜𝜃＜2π, find sec(𝜃/2).

🟠 If csc𝜃 = 8/3 & π/2＜𝜃＜π, find cot(𝜃/2).

🔴 If sec𝜃 = 5/4 & 0º＜𝜃＜90º, find cos(𝜃/2).

P17

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P18

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P18

🔴 If cot(－𝜃)= 0.47, find tan( 𝜃－(π/2) ).
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🟠 If sec𝜃 = －5.76, find csc( 𝜃－(π/2) ).
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🟡 Find the exact value of cos15º by using
the appropriate Angle Sum/Diff Identities.

🟢 Find the exact value of tan15º by using
the appropriate Angle Sum/Diff Identities.

🔵 Simplify: ( tan(3u)－tan(－u) ) / ( 1+ tan(3u)•tan(－u) )

🟣 Simplify: cos(－6v)cos(－5v) + sin(－6v)sin(－5v)

P19

🟣 Find the exact value:
( tan(46º) － tan(1º) ) / ( 1 + tan(46º)•tan(1º) )

🔵 Find the exact value:
sin(22π/9)cos(7π/9) － cos(22π/9)sin(7π/9)

🟢 Find the exact value:
cos(25π/9)cos(10π/9) + sin(25π/9)sin(10π/9)

🟡 If sin𝜃 = －4/5 & 3π＜𝜃＜7π/2, find sin(2𝜃).

🟠 If cos𝜃 = 3/5 & 0＜𝜃＜π, find cos(2𝜃).

🔴 If cos𝜃 =－3/5 & 450º＜𝜃＜540º, find sin(𝜃/2).

P20

🔴 If sin𝜃 = 12/13 & 450º＜𝜃＜540º, find sin(2𝜃).

🟠 If cos𝜃 = √(7)/7 & 270º＜𝜃＜360º, find cos(2𝜃).

🟡 If cos𝜃 = -3/5 & 90º＜𝜃＜180º, find tan(2𝜃).

🟢 If tan𝜃 = -4/3 & 90º＜𝜃＜180º, find tan(𝜃/2).

🔵 If sin𝜃 = 12/13 & π/2＜𝜃＜π, find tan(2𝜃).

🟣 If cos𝜃 = -3/5 & 450º＜𝜃＜540º, find sin(𝜃/2).

P21

💜 Use a half-angle identity to find cos(9π/8).

💙 Use a half-angle identity to find tan(15º).

💚 Use a half-angle identity to find sin(112.5º).

💛 Use a half-angle identity to find tan(23π/12).

🧡 If tan𝜃 = 15/8 & π＜𝜃＜3π/2, find cos(𝜃/2).

❤️ If tan𝜃 = 5√(39)/39 & 3π/2＜𝜃＜2π, find sin(𝜃/2).
↑ ↑ ↑ ↑ error at the end of this video...
(I fix it in the orange heart video.)