回答:
请参阅以下说明
说明:
#6sinA + 8cosA = 10#
将双方分开 #10#
#3 / 5sinA + 4 / 5cosA = 1#
让 #cosalpha = 3/5# 和 #sinalpha = 4/5#
#cosalpha = cosalpha / sinalpha =(3/5)/(4/5)= 3/4的#
因此,
#sinAcosalpha + sinalphacosA = SIN(A +阿尔法)= 1#
所以,
#A +阿尔法= pi / 2之间#, #mod 2PI#
#A = PI / 2-α#
#TANA = TAN(PI / 2-α)= cotalpha = 3/4的#
#TANA = 3/4的#
#QED#
回答:
见下文。
说明:
#或,6sinA - 10 = -8cosA#
#or,(6sinA -10)^ 2 =(-8cosA)^ 2#
#or,36sin ^ 2A- 2 * 6sinA * 10 + 100 = 64cos ^ 2A#
#or,36sin ^ 2A - 120sinA + 100 = 64cos ^ 2A#
#or,36sin ^ 2A - 120sinA + 100 = 64(1 - sin ^ 2A)#
#or,36sinA - 120sinA +100 = 64 - 64Sin ^ 2A#
#or,100 sin ^ 2A - 120SinA + 36 = 0#
#or,(10sinA-6)^ 2 = 0#
#or,10sinA - 6 = 0#
#or,SinA = 6/10#
#或,SinA = 3/5 = p / h#
使用毕达哥拉斯定理,我们得到
#b ^ 2 = h ^ 2 - p ^ 2#
#or,b ^ 2 = 5 ^ 2 - 3 ^ 2#
#or,b ^ 2 = 25 - 9#
#or,b ^ 2 = 16#
#or,b = 4#
#so,TanA = p / b = 3/4#
这个答案是否正确?
回答:
看解决方案
说明:
#6sinA + 8cosA = 10#
将双方分开 #sqrt(6 ^ 2 + 8 ^ 2)#=#10#
#(6sinA)/ 10 + 8cosA / 10 = 10/10 = 1#
#cosalphasinA + sinalphacosA#=1
哪里 #tanalpha = 4/3# 要么 #阿尔法= 53degree#
这转变为
#sin(阿尔法+ A)= sin90#
#alpha + A = 90#
#A = 90-α#
服用 ##晒黑双方
#TANA = TAN(90-α)#
#TANA = cotalpha#
#TANA = 3/4的#
#6sinA + 8cosA = 10#
#=> 3sinA + 4cosA = 5#
#=>(3/5)sinA +(4/5)cosA = 1#
#=>(3/5)sinA +(4/5)cosA =(sinA)^ 2 +(cosA)^ 2#
#color(red)(sin ^ 2A + cos ^ 2A = 1)#
#=>(3/5)sinA +(4/5)cosA = sinA * sinA + cosA * cosA#
#=> sinA = 3/5,cosA = 4/5#
因此, #tanA = sinA / cosA =(3/5)/(4/5)=(3/5)×(5/4)= 3/4#