Mount saint helen is an active stratovolcano and it was formed due to the subduction of the Juan de fuca plate.
4 sinx / cosx * cosx
4 tanx / cosx Trig identity tanx = sinx/cosx
The answer is the Dinosaurs and the Pterosaurs.
The Jurassic Period follows Triassic Period. It is known as the Age of Reptiles. the land was dominated by the dinosaurs and the flying pterosaurs. Both groups are reptiles. Other animals and plants during this period have just recovered from the largest mass extinctions on Earth.