pre calculus
posted by lelelelel .
A parallelogram has a 70 degree angle and sides 6 cm and 10 cm long. How long are its diagonals?

I assume you have had trig. Draw the figure. if it has a 70 degree acute angle, the other angle is 110.
Use the law of cosines:
shortdiag^2=6^2+7^22*6*7Cos70
longdiag^2=6^2+7^22*6*7Cos110