化简 [ sin(270°+B) × sin(90°-B) × cot(B-270°) ] / [ sin(-B) × cos(270°-B) × cot(180°-B) ]要完整,

化简 [ sin(270°+B) × sin(90°-B) × cot(B-270°) ] / [ sin(-B) × cos(270°-B) × cot(180°-B) ]要完整, 化简sin^2(42°+b)-2tan(45°+b)tan(45°-b)+sin^2(48°-b)-cot^2(270°-b) 化简（sin(a-b)-2sin a cos b）/2sin a sin b +coa(a+b) S=1/2×AB×BC×sin∠B=1/2×6×8×sin60°=12√3(√是根号) 其中sin是什么意思 B*S*w*sin wt是什么公式啊?我们只学E*sin wt. 化简sin^2a+sin^2b-sin^2a*sin^2b+cos^2a*cos^2b sin^2a+sin^2b-sin^2a * sin^2b+cos^2a * cos^2b 化简 化简sin（A+B）sin（A-B）要过程答案是sin方A - sin方B 化简cos^4b-sin^4b 如何用MATLAB编写六元一次方程组这是我编的程序,但是不对a=2.578b=40s=82XA=a*(cos(s)+(pi/180)*(s+b)*sin(s))YA=a*(sin(s)-(pi/180)*(s+b)*cos(s))XB=a*(cos(s+180)+(pi/180)*(s+180-b)*sin(s+180))YB=a*(sin(s+180)-(pi/180)*(s+180-b)*cos(s+ 证明sin(a+b)sin(a-b)=sin²a-sin² b,并用该式计算sin²20°+sin80°sin40° sin²20°+sin80°sin40°且sin(a+b)sin(a-b)=sin^2a-sin^2b sin(a+B)cos(y-B)-cos(B+a)sin(B-y) 化简 sin（a+B)sin(B-y)-cos(a-B)cos(y-B) 化简 cos(a+b)+cos(a-b)/sin(a+b)+sin(a-b)化简 化简 cos(a-b)cos(a+b)+sin(a-b)sin(a+b). cos(a-b)cos(a+b)+sin(a-b)sin(a+b)化简, 化简,sin(a+b)cos(r-b)-cos(b+a)sin(b-r)