if 7 sin²θ + 3 cos²θ = 4 then find value of tanθ
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Step-by-step explanation:
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Answer:
7sin²Ɵ+3cos²Ɵ=4
Step-by-step explanation:
∵sin²Ɵ+cos²Ɵ=1
7sin²Ɵ+3(1-sin²Ɵ)=4
7sin²Ɵ+3-3sin²Ɵ=4
4sin²Ɵ=1
sin²Ɵ=1/4
sinƟ=±1/2
sinƟ=1/2 or (-1/2)
substituting sinƟ in given eq.n;
4-7(1)=3cos²Ɵ
2
4-7=3cos²Ɵ
2
8-7 =3cos²Ɵ
2
1 =cos²Ɵ
6
cosƟ=±1/√6; when sinƟ=(-1/2)
4-7(-1)=3cos²Ɵ
2
4+7=3cos²Ɵ
2
8
8+7=3cos²Ɵ
2
cos²Ɵ=15 = 5
6 2
cos²Ɵ=±5/2; when sinƟ=(1/2)
∵tanƟ=sinƟ/cosƟ
Thus, tanƟ=1 ÷ 5 = 1 (if cosƟ=+5/2)
2 2 5
OR tanƟ=(-1/5) { if cosƟ=-5/2}
tanƟ= (-1/2)÷(1/√6)=(-√6/2)
tanƟ= (-1/2)÷(-1/√6)=(+√6/2)
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