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A kite is flying in the sky. A person is holding the kite with 40 m long tightly stretched string. Find the height of the kite (in meters) if the angle made by the string with the horizontal is 30 degrees.
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In a 30-60-90 triangle, the sides are in the ratio 1: 3тАЛ: 2. Since the hypotenuse (2 units) is 40 m, the side opposite 30 degrees (1 unit) must be 40 / 2 = 20 m.
Length of the string (hypotenuse) l = 40 m, angle of elevation (theta) = 30 degrees.
sin(╬╕)=HypotenuseHeightтАЛ
In a 30-60-90 triangle, the sides are in the ratio 1: 3тАЛ: 2. Since the hypotenuse (2 units) is 40 m, the side opposite 30 degrees (1 unit) must be 40 / 2 = 20 m.
Students often confuse the sine ratio (opposite/hypotenuse) with the cosine ratio (adjacent/hypotenuse) or incorrectly identify the string as the height rather than the hypotenuse.
Identify the Triangle Components
Represent the situation as a right-angled triangle where the string is the hypotenuse, the height of the kite is the opposite side, and the angle is 30 degrees.
Hypotenuse=40,╬╕=30┬░
Apply Sine Ratio
Use the definition of sine for the angle of elevation: sin(30┬░)=HypotenuseHeightтАЛ.
sin(30┬░)=40hтАЛ
Calculate the Result
Substitute the value of sin(30┬░)=0.5 into the equation and solve for h.
h=40├Ч0.5=20┬аm
A is correct because the calculation based on the trigonometric ratio sin(30┬░)=h/40 yields a height of 20 m.
This concept is fundamental to Height and Distance problems; mastering the 1: 3тАЛ: 2 ratio for 30-60-90 triangles will save significant time in competitive exams.