Question

If x tan- 120° + 4cos 150º = 9. then x =
a) 1
b) 2
d)-2
c)-1

with explanation​

Answer 1

Step-by-step explanation:

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vishwajeetsinghmani2

pranav6431

16.03.2020

Math

Secondary School

+5 pts

Answered

If x tan² 120° + 4cos2 150° = 9, then x is

2

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marklags

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Answer:

-2

Step-by-step explanation:

tan² (∅)= [1+cos(2∅) ]/ [1−cos(2∅) ]

cos²(∅)= (1/2)[1+cos (2∅)]

so,

x[1+cos{2(120°)}]/[1-cos{2(120°)}] + (4)(1/2)[1+cos{2(150°)}] = 9

x[1.5/-.5]+(4)[1.5]=9

x(-3)+3=9

-3x=6

x=-2