90 POINT QUESTION!!!

Mathematics

1 answer:

Aleks [24]2 years ago

7 0

Answer: 9.19 ft

Step-by-step explanation:

Hi, since the situation forms a right triangle (see attachment) we have to apply the next trigonometric function.

Sin α = opposite side / hypotenuse

Where α is the angle of elevation of the ladder to the ground, the hypotenuse is the longest side of the triangle (in this case is the length of the ladder), and the opposite side (x) is the height of the top of the ladder above the ground.

Replacing with the values given:

Sin 45 = x/ 13

Solving for x

sin45 (13) =x

x= 9.19 ft

Feel free to ask for more if needed or if you did not understand something.

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vaieri [72.5K]

I DON'T UNDERSTAND MATH ANYMORE!!!!!!!!

7 0

3 years ago

The heat developed in an electric wire varies jointly as the wires resistance, the time the current flows, & the square of t

never [62]

Answer:

4 ohms

Step-by-step explanation:

The question is "In two minutes a current of 5 amps develops 1,200 heat units in a wire of 8 ohms resistance. What resistance does a similar wire have, which develops 6,000 heat units with a current of 10 amps in 5 minutes?"

Current, I₁ = 5 A

Heat, Q₁ = 1200 units

Resistance, R₁ = 8 ohms

Time, t₁ = 2 min = 120 s

New heat, Q₂ = 6000 units

Current, I₂ = 10 A

New time, t₂ = 5 min = 300 s

We need to find the new resistance.

Heat developed is given by :

$Q=I^2Rt$

$\dfrac{Q_1}{I_1^2R_1t_1}=\dfrac{Q_2}{I_2^2R_2t_2}\\\\R_2=\dfrac{Q_2\times I_1^2R_1t_1}{Q_1I_2^2t_2}\\\\R_2=\dfrac{6000\times 5^2\times 8\times 120}{1200\times 10^2\times 300}\\\\=4\ \Omega$