Q. Given secA=661 and that angle A is in Quadrant I, find the exact value of cscA in simplest radical form using a rational denominator.
Understand relationship sec A cos A: Understand the relationship between sec A and cos A.Secant is the reciprocal of cosine.secA=cosA1Given secA=661, we can find cos A by taking the reciprocal of sec A.
Calculate cosA: Calculate cosA. cosA=secA1 cosA=(661)1 cosA=616 To rationalize the denominator, multiply the numerator and denominator by 61. cosA=(616)×(6161) cosA=616×61
Use Pythagorean identity find sin A: Use the Pythagorean identity to find sinA. The Pythagorean identity states that sin2A+cos2A=1. We know cosA, so we can solve for sin2A. sin2A=1−cos2Asin2A=1−(616⋅61)2sin2A=1−61⋅6136⋅61sin2A=1−372136⋅61sin2A=37213721−2196sin2A=37211525 Since A is in Quadrant I, sinA is positive. sin2A+cos2A=11sin2A+cos2A=12
Find cscA: Find cscA, which is the reciprocal of sinA. cscA=sinA1 cscA=(1525/61)1 To rationalize the denominator, multiply the numerator and denominator by 1525. cscA=(152561)⋅(15251525) cscA=(152561⋅1525)
Simplify expression cscA: Simplify the expression for cscA. We need to simplify 1525. Since 1525=25×61, we can take the square root of 25 out of the radical. cscA=152561×25×61cscA=152561×5×61cscA=1525305×61 Now, simplify the fraction by dividing both the numerator and the denominator by 305. cscA=561
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