The mean of four numbers is 71.5 if three of the numbers are 58,76,and 88, what is the value of the fourth number
1 answer:
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(tanθ + cotθ)² = sec²θ + csc²θ
<u>Expand left side</u>: tan²θ + 2tanθcotθ + cot²θ
<u>Evaluate middle term</u>: 2tanθcotθ = = 2
⇒ tan²θ + 2+ cot²θ
= tan²θ + 1 + 1 + cot²θ
<u>Apply trig identity:</u> tan²θ + 1 = sec²θ
⇒ sec²θ + 1 + cot²θ
<u>Apply trig identity:</u> 1 + cot²θ = csc²θ
⇒ sec²θ + csc²θ
Left side equals Right side so equation is verified
Answer:
(- 2, 6 )
Step-by-step explanation:
Given the equations
3x + 2y = 6 → (1)
y - x = 6 ( multiply through by 3 to clear the fraction )
2y - 3x = 18 ( add 3x to both sides )
2y = 18 + 3x → (2)
Substitute 2y = 18 + 3x into (1)
3x + 18 + 3x = 6
6x + 18 = 6 ( subtract 18 from both sides )
6x = - 12 ( divide both sides by 6 )
x = - 2
Substitute x = - 2 into (1) and solve for y
3(- 2) + 2y = 6
- 6 + 2y = 6 ( add 6 to both sides )
2y = 12 ( divide both sides by 2 )
y = 6
solution is (- 2, 6 )