PWEASE HELP ME, AREA OF A CIRCLE

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?

The? half-life of a radioactive substance is 20 years. if you start with some amount of this? substance, what fraction will remain in 120 ? years

The actual length of side y is 22 cm. use the scale drawing to find the actual length of side x. a) 15.2 cm b) 17.1 cm c) 18.0 cm d) 28.3 cm