okay so I got angry at a post on birbsite with "vintage lgbtq pins". I search for the image and found a reddit thread (https://www.reddit.com/r/bisexual/comments/car38y/vintage_pride_pins_peep_that_bisexual_pride/) with multiple links to an etsy shop (https://www.etsy.com/listing/537000786/set-of-4-bisexual-pride-lgbt-bi-pin?gpla=1&gao=1&&utm_source=google&utm_medium=cpc&utm_campaign=shopping_us_e-accessories-patches_and_pins-pins_and_pinback_buttons&utm_custom1=_kenshoo_clickid_&utm_content=go_304499315_22746176315_78727406915_pla-106551384275_m__537000786&gclid=EAIaIQobChMI8u65_cam4wIVDI7ICh2OOQHAEAQYFyABEgIiw_D_BwE#) were you can buy the exact same "vintage" bisexual triangles pin.

so does anyone know when the biangles/bisexual triangles were invented? like, for sure?
https://gayety.co/what-is-the-bisexual-symbol claims it was 1987, but that seems very early? (same year as the rainbow flag)