Complete question is;
A 21 ft ladder is leaning against a tall wall with the foot of the ladder placed at 7 feet from the base of the wall and the angle of elevation is?
Answer:
θ = 70.5°
Step-by-step explanation:
The angle of elevation simply means the angle that the ladder makes with the ground. Let's call this angle θ.
I've attached a diagram showing the triangle made by this ladder and the wall.
From the attached diagram, we can see the triangle formed by the ladder and the wall.
We can find the angle of elevation θ from trigonometric ratios.
Thus;
7/21 = cos θ
cos θ = 0.3333
θ = cos^(-1) 0.3333
θ = 70.5°
4a + 6b = 10
2a - 4b = 12...multiply by -2
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4a + 6b = 10
-4a + 8b = - 24 (result of multiplying by -2)
------------------add
14b = - 14
b = -14/14
b = -1
2a - 4b = 12
2a - 4(-1) = 12
2a + 4 = 12
2a = 12 - 4
2a = 8
a = 8/2
a = 4
so 12a = 12(4) = 48 <==
We are given with the rate of change of the base, db/dt equal to 1 ft/ sec and the rate of change of the height of the triangle, dh/dt equal to 2 ft/sec. b is 10 ft and h is 70 ft. Area of triangle is equal to A= 0.5 bh The rate of change of the area is equal to dA/dt = 0.5 b dh/dt + 0.5 h db/dt. Substituting, dA= 0.5*10*2 + 0.5*70 * 1 equal to 45 ft2 / sec.
5( y + 2/5) = -13
Distribute the 5 by multiplying the 5 by each term inside the set of parentheses:
5y + 2 = -13
Subtract 2 from both sides:
5y = -15
Divide both sides by 5:
Y = 3
The answer is y = 3
1.6 × 1.6 × 1.6 × 1.6 = 6.5536