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问题: 数学7

要有步骤

解答:

24、
C=180-(A+B)--->sinC=sin(A+B)=(√6+√2)/4
--->c/sinC = 16/(√6+√2) = 4(√6-√2)
a = sinA(c/sinC) = 4(√3-1)
b = sinB(c/sinC) = 2(3√2-√6)
R = (c/sinC)/2 = 2(√6-√2)
S = (1/2)bcsinA = 4(3-√3)

25、
b=2a--->sinB = sin2A = sin(A+60)
--->2A=A+60--->A=60°
或:2A+(A+60)=180--->A=40°

--->A = 60°或40°