A pair of boots were $45 they were on sale for $38.25 what percent were they off
2 answers:
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Answer:
L.S = R.S ⇒ Proved down
Step-by-step explanation:
Let us revise some rules in trigonometry
- sin²α + cos²α = 1
- sin2α = 2 sin α cosα
- cscα = 1/sinα
To solve the question let us find the simplest form of the right side and the left side, then show that they are equal
∵ L.S = csc2α + 1
→ By using the 3rd rule above
∴ L.S = + 1
→ Change 1 to
∴ L.S = +
→ The denominators are equal, then add the numerators
∴ L.S =
∵ R. S =
∵ (sinα + cosα)² = sin²α + 2 sinα cosα + cos²α
∴ (sinα + cosα)² = sin²α + cos²α + 2 sinα cosα
→ By using the 1st rule above, equate sin²α + cos²α by 1
∴ (sinα + cosα)² = 1 + 2 sinα cosα
→ By using the 2nd rule above, equate 2 sinα cosα by sin2α
∴ (sinα + cosα)² = 1 + sin2α
→ Substitute it in the R.S above
∴ R. S =
∵ L.S = R.S
∴ csc 2α + 1 =