Given that cosA=32 and cosB=630, and that angles A and B are both in Quadrant I, find the exact value of sin(A−B), in simplest radical form.Answer:
Q. Given that cosA=32 and cosB=630, and that angles A and B are both in Quadrant I, find the exact value of sin(A−B), in simplest radical form.Answer:
Use Cosine Subtraction Formula: Use the cosine subtraction formula to find sin(A−B). The cosine subtraction formula is cos(A−B)=cos(A)cos(B)+sin(A)sin(B). Since we are looking for sin(A−B), we need to use the sine and cosine values to find sin(A) and sin(B) first.
Find Sine Values: Find sin(A) and sin(B) using the Pythagorean identity.The Pythagorean identity is sin2(θ)+cos2(θ)=1.For angle A:sin2(A)=1−cos2(A)sin2(A)=1−(32)2sin2(A)=1−92sin2(A)=99−92sin2(A)=97sin(A)=97sin(A)=37For angle B:sin(B)0sin(B)1sin(B)2sin(B)3sin(B)4sin(B)5sin(B)6sin(B)7
Apply Sine Subtraction Formula: Apply the sine subtraction formula. The sine subtraction formula is sin(A−B)=sin(A)cos(B)−cos(A)sin(B). Substitute the values we found for sin(A), cos(A), sin(B), and cos(B): sin(A−B)=(7/3)⋅(30)/6−(2)/3⋅(6)/6
Simplify Expression: Simplify the expression.sin(A−B)=3⋅67⋅30−3⋅62⋅6sin(A−B)=18210−1812sin(A−B)=18210−12sin(A−B)=18210−2⋅3sin(A−B)=18210−2⋅3
Simplify Radicals: Simplify the radicals if possible. 210 can be simplified to 2×3×5×7=2×3×5×7=6×35 So, sin(A−B)=(6×35−2×3)/18sin(A−B)=(6×35)/18−(2×3)/18sin(A−B)=(210)/18−(2×3)/18 We already simplified 210 earlier, so this step does not change the expression.
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