Question

The lengths of the three sides of a right triangle form a geometric sequence. The sine of the smallest of the angles in the triangle is

Answers

  1. The sine of the smallest of the angles in the triangle is;
    SinA = √{(√5 – 1)/2}.

    What is geometric sequence?

    A unique kind of sequence called a geometric sequence has a constant ratio between every two succeeding terms. This ratio is regarded as one of the geometric sequence’s common ratios.
    • In other words, each phrase in a geometric series is multiplied by the a constant to produce the following term.
    • Therefore, a geometric series has the formula a, ar, ar², where an is the initial term as well as r is the sequence’s common ratio.
    • Either one positive or negative integer can be used to describe the common ratio.
    Now, according to the question;
    Consider right angled triangle ΔABC ; right angled at C.
    The side opposite to each vertices A,B,C are a, b, c respectively.
    Thus, by Pythagorean theorem,
    a² + b² = c²   (equation 1)
    By geometric sequence;
    a² = bc (say);
    Also, a/c = √(b/c)
    substitute  in equation 1
    b² + bc – c² = 0
    Divide equation by c².
    b²/c² + b/c – 1 = 0  (equation 2)
    Consider vertex B.
    The sine of angle B; sinB = Perpendicular/Hypotenuse
    SinB = b/c = t (say)
    Substitute b/c by t in equation 2
    t² + t -1 = 0
    Calculate the roots of the equation by quadratic formula;
    t = (√5 – 1)/2 and (-√5 – 1)/2 (negative value is not possible for side)
    Thus, t = (√5 – 1)/2
    Also SinA = a/c = √(b/c)
    SinA = √{(√5 – 1)/2}
    Therefore, the sine of the smallest of the angles in the triangle is;
    SinA = √{(√5 – 1)/2}.
    To know more about geometric sequence, here
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