Do you think nixon's policy of détente was good or bad for the united states? why or why not? do you think reagan's strategic defense initiatives was a good or bad idea? why or why not?

Detente was a better policy than a continuation of nuclear proliferation and escalating the tensions of the Cold War.  Nixon sought to reduce tensions with the USSR by meeting with Soviet premier Leonid Brezhnev in 1972 -- the first US president to visit Moscow.  Nixon also visited China in 1972 to begin a process of normalizing relations with that communist country.

Reagan's proposal of the Strategic Defense Initiative (SDI) in 1983 tended to escalate tensions again between the United States and the Soviet Union.  Reagan's proposed idea of a space-based missile defense shield seemed to the Soviets to be a violation of agreements in Strategic Arms Limitations Talks (SALT) that had already been agreed upon.  According to the US Department of State archives, Reagan's commitment to SDI became a barrier to the US and USSR reaching agreement on arms limitations measures.  The Strategic Arms Reduction Treaty (START) was completed after Reagan left office. 
Some have suggested that SDI applied sufficient pressure to the USSR to help bring the Cold War to an end, but that claim is hard to substantiate.