LtSpice antisymmetric sine pulse
This is not a very beautiful approach, but it works (for this signal).

First I created two voltage sources, which provide the two halves of the signal.

So V1 is SINE(0 8 25k 0 0 0 0.25), a 25 kHz sine but only for a quarter cycle, so that it stops at the maximum value.

V2 is SINE(0 8 16k6667 10u 0 90 0.25), 16.67 kHz sine but shifted by 90° so it starts at the maximum, again for a quarter cycle, so that it will stop at zero.

The real output is then a BV-source with V=min(V(Vout1),V(Vout2)) so it outputs always the smaller of the two voltages, which works in this case because one starts at the maximum value and the other one stops at the maximum value.

The frequencies are easy to calculate: it's just \$f = \frac{1}{4 \times t}\$ where t is either the rise or the fall time.