I have tried to find a book that would cover high school math together with some tricky problems. I have a cousin who hasn't studied math in about 10 years, but he needs to do the GRE. He wanted to start reviewing in a way that would actually teach the math instead of just showing tricks that you need to memorize. The other issue is that he studied math in another language, so he doesn't know the english terminology. He's going to do the GRE in the spring, so there's really no hurry. Euclidean geometry is especially a weak spot, because it's almost completely neglected in the curricula he followed in school. He did place in the top 5% nationally in math at the time he graduated high school, so he's completely capable of learning. I know there are these review books for math grads i.e. "All the math you need for grad school" etc. so I was wondering if there's something similar for the high school level i.e. something concise but still complete.