$$[ \cos ^ { - 1 } \frac { 4 } { 5 } + \tan ^ { - 1 } \frac { 2 } { 3 } ]$$
$\frac{632211610923993040000000000000000}{7271824520778109794986870956743}\approx 86.939888211$
$\frac{23633 \cdot 334390265161 \cdot 2 ^ {19} \cdot 5 ^ {16}}{281297 \cdot 17773074793 \cdot 53870617912429 \cdot 3 ^ {3}} = 86\frac{6.834702137075628 \times 10^{30}}{7.27182452077811 \times 10^{30}} = 86.9398882106611$
