Q. Given cotA=−1715 and that angle A is in Quadrant IV, find the exact value of sinA n simplest radical form using a rational denominator.Answer____
Use Pythagorean Identity: Use the Pythagorean identity for cotangent and sine: cot2(A)+1=csc2(A). Since we know cotA, we can find cscA and then sinA.
Calculate csc2(A): Calculate csc2(A) using the identity: csc2(A)=cot2(A)+1. Substitute cotA=−1715 into the identity. csc2(A)=[−1715]2+1csc2(A)=17125+1csc2(A)=17125+171171csc2(A)=171196
Find csc(A): Find csc(A) by taking the square root of csc2(A). csc(A)=171196 csc(A)=171196 csc(A)=17114 Since we need a rational denominator, rationalize the denominator. csc(A)=(17114)⋅(171171) csc(A)=17114171
Find sin(A): Since csc(A) is the reciprocal of sin(A), we can find sin(A) by taking the reciprocal of csc(A). sin(A)=csc(A)1 sin(A)=(17114171)1 sin(A)=14171171
Simplify sin(A): Simplify the expression for sin(A) by dividing both the numerator and the denominator by the greatest common divisor, which is 14. sin(A)=14171/14171⋅14 sin(A)=14171/171 sin(A)=14171⋅1711 sin(A)=14⋅171171
Include negative sign: Since angle A is in Quadrant IV, sinA must be negative. Therefore, we must include the negative sign in our final answer.sin(A)=−14171171
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