3 An arithmetic progression (AP) and a geometric progression (GP) have the same first and fourth terms as each other. The first term of both is 1.5 and the fourth term of both is 12 . Calculate the difference between the tenth terms of the AP and the GP.
\begin{figure}[h]
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\caption{Fig. 4}
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Fig. 4 shows triangle ABC , where \(\mathrm { AB } = 7.2 \mathrm {~cm} , \mathrm { AC } = 5.6 \mathrm {~cm}\) and angle \(\mathrm { BAC } = 68 ^ { \circ }\).
Calculate the size of angle ACB .