A ladder rests against the top of a perpendicular wall of a ...?

2017-02-03 7:04 pm
A ladder rests against the top of a perpendicular wall of a building and makes an angle of 73o with the ground. If the foot of the ladder is 2m from the wall. Calculate:
The height of the building,
The length of the ladder

回答 (5)

2017-02-03 7:35 pm
tan73° = (opposite side) / (adjacent side)
tan73° = (height of the building) / (2 m)
Then, height of the building = 2 tan73° m = 6.5 m
2017-02-03 7:21 pm
Let L be the length of the ladder. 2/L = cos73 -----> L = 2/cos73 = 6.84m
The height of the building = L*sin73 = 6.54m
2017-02-03 10:50 pm
https://gyazo.com/2ee27df4a28772a8f53571e29ee4ed48

tan(73) = height / 2
height = 2 * tan(73)
height = 6.54 m

To find the length of the ladder use the Pythogorean theorem
(6.54)^2 + 2^2 = ladder^2
ladder^2 = 42.7716 + 4 = 46.7616
ladder = sqrt(46.7616) = 6.84 m
2017-02-03 10:07 pm
tan 73⁰ = x / 2
x = 2 tan 73 ⁰
x = 6•54 m______height of building

y² = 6•54² + 2²
y = 6•84 m______length of ladder
2017-02-03 8:27 pm
Use the Trig. Function 'Tangent'.
Tan(73) = h/2
h = 2Tan(73)
h = 2(3.2708526184841408653088562573054)
h = 2(3.27)
h = 6.54 m

The length of the ladder can by done by two methods.#1 Trig. using Cosine function, or #2 by Pythagoras.

#1
Cos(73) = 2/L
L = 2/Cos(73)
L = 2/ 0.2923...
L = 6.84 m

or #2
L^2 = 2^2 + 6.54^2
L^2 = 4 + 42.776...
L^2 = 46.776...
L = 6.84 m


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