Use the law of cosines to find the length of side c. With a triangle with side b = 21cm and side a = 15cm and angle C = 23

c = 9.28 cm

Step-by-step explanation:

c^2 = a^2 + b^2 - 2abcosC law of cosines

c^2 = 15^2 + 21^2 - 2*15*21 * cos23

c^2=225+441-630 *.9205

combine like terms

c^2 = 666 - 86.08579.92

c^2 = 86.09

take the square root of each side

sqrt (c^2) = sqrt (86.09)

c = 9.28