Anyone know this? i dont get it

In triangle △abc, ∠abc=90°, bh is an altitude. find the missing lengths. ab=4 and bc=3, find ah, ch and bh.

Write an introductory paragraph for this corrie ten boom and her family were faced with some difficult choices after hitler came to power. some family members paid the ultimate price. write a carefully thought-out paper of at least 200 words dealing with the following concepts: --how should a christian act when evil is in power? --what do you think it would be like to live in an occupied country? remember to proofread anything you write thoroughly.

3x + 4y = 5 x- 3y = -7 solve by substitution