St G Study Guide Name ________________________ Trigonometry
Verifying Identities
→ Change everything to sine and cosine ▪ Combine fractions
→ Use Pythagorean ID
→ Factor (GCF)
→ Starting with the fraction… ▪ If (+) or (–) in numerator→Split up fractions ▪ If (+) or (–) in denominator→ Multiply by the conjugate (to create a pythag ID)
Verify each identity below.
17) 1
1−sin𝑥= sec2 𝑥 + tan 𝑥 sec 𝑥
18) −sec 𝑥 − tan2 𝑥 sec 𝑥 = −sec3 𝑥
19)
20) cos 𝑥 cot 𝑥 = sec 𝑥 cot 𝑥 − sin𝑥
21) 1+cos𝑦
sec𝑦= cos𝑦 + cot2 𝑦
22) sec2 𝑥 + tan2 𝑥 =1+sin2 𝑥
cos2 𝑥
23)
24) sin𝑥
1+cos𝑥=
1−cos𝑥
sin𝑥
25)
26)
27)
28)
29) Which line of reasoning is correct when verifying the identity shown below? sec x – sec x sin2 x = cos x ?
a.
b.
c.
d.
Evaluating Expressions Determine the exact value of each expression (meaning no decimals!).