C This program finds triangle angles

C opposite given sides (exercise 2.9.13).

C

C prompt for and read the side lengths

PRINT *,sides:

READ *,SA,SB,SC

C

C use law of cosines to find the angles

CA=(SB**2 + SC**2 - SA**2)/(2.*SB*SC)

A=ACOS(CA)

CB=(SA**2 + SC**2 - SB**2)/(2.*SA*SC)

B=ACOS(CB)

CC=(SA**2 + SB**2 - SC**2)/(2.*SA*SB)

C=ACOS(CC)

PRINT *,cosines:

PRINT *,CA,CB,CC

C

C convert angles to degrees for output

PI=4.*ATAN(1.)

DPR=180./PI

A=DPR*A

B=DPR*B

C=DPR*C

PRINT *,opposite angles:

PRINT *,A,B,C

STOP

END

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