Wiil or going to help me please~~

1. ∠1 is complementary to ∠2 and ∠3 is complementary to ∠2. subtraction property of equality 2. m∠1 + m∠2 = 90 and m∠3 + m∠2 = 90 substitution 3. m∠1 + m∠2 = m∠3 + m∠2 definition of complementary 4. m∠1 = m∠3 given

What are the triple angle formulas? is it related to double angle identities?

The angle of depression from the top of the tree to the tip of the shadow is 25°. find the height of the tree to the nearest tenth. a. 16.8 feet b. 18.2 feet c. 23.4 feet d. 39.7 feet