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a cos^2(C/2) + c cos^2(A/2) = s, and sides in A.P.

This type of question, asked 3 times: 11 May 2023 S2, 11 May 2024 S1, 16 Apr 2026 S1. All 3 questions below, oldest first.

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  1. Question 1

    11 May 2023 S2

    139
    If the sides of a triangle a,b,ca,b,c are in A.P., then with usual notations, acos⁡2C2+ccos⁡2A2a\cos^2\frac{C}{2}+c\cos^2\frac{A}{2} is

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  2. Question 2

    11 May 2024 S1

    132
    In △ABC\triangle ABC, with usual notations, if acos⁡2C2+ccos⁡2A2=3b2a\cos^2\frac{C}{2} + c\cos^2\frac{A}{2} = \frac{3b}{2}, then

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  3. Question 3

    16 Apr 2026 S1

    62
    With usual notations in △\triangleABC, if bcos⁡2C2+ccos⁡2B2=3a2b\cos^2\dfrac{C}{2} + c\cos^2\dfrac{B}{2} = \dfrac{3a}{2} then

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