Question

[nguyễn thị minh ánh]

Tính giá trị các biểu thức sau:

1. A=\(\left(sin1^o+sin2^o+sin3^o+...+sin88^o+sin89^o\right)-\left(cos1^o+cos2^o+cos3^o+...+cos88^o+cos89^o\right)\)

2. B= \(\left(tan1^o.tan2^o.tan3^o...tan87^o.tan88^o.tan89^o\right)\)

3. C=\(cot1^o.cot2^o.cot3^o...tan87^o.tan88^o.tan89^o\)

4. D= \(sin^21^o+sin^22^o+sin^23^o+...+sin^287^o+sin^288^o+sin^289^o\)

5. E = \(cos^21^o+cos^22^o+cos^23^o+...+cos^287^o+cos^288^o+cos^289^o\)

Answer 1

[Nguyễn Tấn An]

4. \(D=sin^21^o+sin^22^o+sin^23^o+...+sin^287^o+sin^288^o+sin^289^o=\left(sin^21^o+sin^289^o\right)+\left(sin^22^o+sin^288^o\right)+...+\left(sin^244^o+sin^246^o\right)+sin^245^o=1+1+1+...+1+1+0,5=44,5\)

Answer 2

[Nguyễn Tấn An]

\(5.E=cos^21^o+cos^22^o+cos^23^o+...+cos^287^o+cos^288^o+cos^289^o=\left(cos^21^o+cos^289^o\right)+\left(cos^22^o+cos^288^o\right)+...+\left(cos^244^o+cos^246^o\right)+cos^245^o=1+1+1+...+1+0,5=1.44+0,5=44,5\)