10th grade
posted by it's me .
Triangle ABC is an equilateral triangle.AD=10 What is the length of CD? Give your answer to the nearest whole number.

Please type your subject in the School Subject box. Any other words, including obscure abbreviations, are likely to delay responses from a teacher who knows that subject well.

The School Subject is NOT 10th grade. Is it math? If so, state that for a math teacher to help you.
Sra 
Do not know where D is. Needs more explanation.