Extract the answer to the question from the following context. Question: What is geometry based on? Context: Three Han mathematical treatises still exist. These are the Book on Numbers and Computation, the Arithmetical Classic of the Gnomon and the Circular Paths of Heaven and the Nine Chapters on the Mathematical Art. Han-era mathematical achievements include solving problems with right-angle triangles, square roots, cube roots, and matrix methods, finding more accurate approximations for pi, providing mathematical proof of the Pythagorean theorem, use of the decimal fraction, Gaussian elimination to solve linear equations, and continued fractions to find the roots of equations.
Ans: Han mathematical treatises

Extract the answer to the question from the following context. Question: How much security was required for the torch? Context: Pakistan: The Olympic torch reached Islamabad for the first time ever on April 16. President Pervez Musharraf and Prime Minister Yousaf Raza Gillani spoke at the opening ceremony of the relay. Security was high, for what one newspaper called the "most sensitive leg" of the torch's Olympic journey. The relay was initially supposed to carry the torch around Islamabad, but the entire relay was cancelled due to security concerns regarding "militant threats or anti-China protests", and replaced by an indoors ceremony with the torch carried around the track of Jinnah Stadium. In fear of violent protests and bomb attacks, the torch relay in Pakistan took place in a stadium behind closed doors. Although the relay was behind closed doors, thousands of policemen and soldiers guarded the flame. As a consequence, no incidents arose.
Ans: thousands of policemen and soldiers

Extract the answer to the question from the following context. Question: What is a concern? Context: In an effort to conserve water, Tucson is recharging groundwater supplies by running part of its share of CAP water into various open portions of local rivers to seep into their aquifer. Additional study is scheduled to determine the amount of water that is lost through evaporation from the open areas, especially during the summer. The City of Tucson already provides reclaimed water to its inhabitants, but it is only used for "applications such as irrigation, dust control, and industrial uses." These resources have been in place for more than 27 years, and deliver to over 900 locations.
Ans: the amount of water that is lost

Extract the answer to the question from the following context. Question: Although an unknown number of protesters died,which were acknowledged by the SSR? Context: On the next day, December 18, protests turned into civil unrest as clashes between troops, volunteers, militia units, and Kazakh students turned into a wide-scale confrontation. The clashes could only be controlled on the third day. The Almaty events were followed by smaller protests and demonstrations in Shymkent, Pavlodar, Karaganda, and Taldykorgan. Reports from Kazakh SSR authorities estimated that the riots drew 3,000 people. Other estimates are of at least 30,000 to 40,000 protestors with 5,000 arrested and jailed, and an unknown number of casualties. Jeltoqsan leaders say over 60,000 Kazakhs participated in the protests. According to the Kazakh SSR government, there were two deaths during the riots, including a volunteer police worker and a student. Both of them had died due to blows to the head. About 100 others were detained and several others were sentenced to terms in labor camps. Sources cited by the Library of Congress claimed that at least 200 people died or were summarily executed soon thereafter; some accounts estimate casualties at more than 1,000. The writer Mukhtar Shakhanov claimed that a KGB officer testified that 168 protesters were killed, but that figure remains unconfirmed.
Ans: a volunteer police worker and a student