In △ ABC, Sina * SINB = cos ^ 2 (C / 2), C = 4, C = 40 ° to find the value of A

In △ ABC, Sina * SINB = cos ^ 2 (C / 2), C = 4, C = 40 ° the value of a is Sina * SINB = (1 + COSC) / 22sinasinb = 1-cos (a + b) = 1-cosacosb + sinasinbcosb + sinasib = 1cos (a-b) = 1, A-B = 0, so a = b = 70 °, C = 4, C = 40 ° a = csina / sinc = 4sin70 ° / sin40 °

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