Estimating with multiplying decimals estimate 2.7 times 4

What is sin 7x/4 ? i need on this urgent trig

Thales was an ancient philosopher familiar with similar triangles. one story about him says that he found the height of a pyramid by measuring its shadow and his own shadow at the same time. if the person is 5-ft tall, what is the height of the pyramid in the drawing?

Write a function for a rotation 90 degrees counter clockwise about the origin, point 0