If cos(a) = 2/3,find the value of cos(4a)

If cos(a) = 2/3,find the value of cos(4a) 微积分Find the intervalConsider the function below.(Round the answers to two decimal places.If you need to use - or ,enter -INFINITY or INFINITY.) f(θ) = 2cos(θ) + (cos (θ))^20 ≤ θ ≤ 2π (a) Find the interval of increase.Find the interval tanθ/(1+〖tan〗^2 θ)≡sinθcosθ(1-(〖tan〗^(2 ) 60)/sin30)〖cos〗^245sinθ=7/25 find the value of 3tanθ-1/cosθ by using 勾股定理(tanθ/cosθ+sinθ/(〖cos〗^2 θ ))×〖cos〗^2θCos(40-3θ)=sin(7θ+2)If tanA=5/3 find the value of 4s Find the minimum value of A=x^2 + y^2 if x + y =10 关于COS TAN SIN1.If tan口萨=5/12,then find exact values of cos口萨,sin口萨,and then find the angle口萨 to the nearest degree.2.If cos口萨=-4/5 and 90° 关于相反数.关于opposite number.If |a|=4,|b|=3,a>b,find the value of (a+b) what if you cannot find a job? If A is an angle such that sec(A) + tan(A) = 2,evaluate cos(A)求 COA A.求 COS..A 请写具体 证明：cos平方A+cos平方(60-A)+cos平方(60+A)=3/2 若COS(A+B)COS(A-B)=1/3,则COS^2A-COS^2B=多少 excel表格 =IF(ISERR(FIND(1,a1)),,A)这个公式如果我要a1包含2的时候 结果要b怎么写公式我试了=IF(ISERR(FIND(1,a1)),,A)+IF(ISERR(FIND(2,a1)),,B)但是不行 由cos(a+b)=cos a cos b-sin a sin b cos(a-b)=cos a cos b+sin a sin b解题设a为锐角,证：1、2分之根3乘cos a + 2分之1乘sin a=cos(6分之π-a)2、cos a-sin a=根号2cos(4分之π+a) 已知tan(a)=3,求sin^2(a)+2sin(a)cos(a)+3cos^2(a)/sin(a)cos(a)+cos^2(a)的值 三角函数 求证:cos^2(a)-cos(2a)*cos(4a)=sin^2(3a)求证:cos^2(a)-cos(2a)*cos(4a)=sin^2(3a) tan a=2,(3sin a-cos a)/(2sin a+cos a)= 1-cos2a=?cos(-π-a)=?cos(3π/2-a)=?sin^2a-cos^2a=? 已知sin(3π+a)=1/4,求[cos(π+a)]/{cosa[cos(π+a)-1]}+[cos(a-2π)]/[cos(a+2π)cos(π+a)+cos(-a)]的值要具体过程 证明（3－4cos 2A＋cos 4A） / （3＋4cos 2A＋cos 4A）=tan^4 A