Which equation is not an identity? (a.) tan(–t) = –tan t (b.) tan t(csc t + cot t) = sec t + 1 (c.) sin tcot t = cos t (d.) cos2t − sin2t = –1

  (D.)  cos²(t) − sin²(t) = –1

Step-by-step explanation:

The "Pythagorean identity" for sine and cosine is ...

  cos²(t) + sin²(t) = 1

Changing the sign makes it not be an identity.

A makes use of the fact that tangent is an odd function.

B makes use of cot=1/tan and tan=sec/csc.

C makes use of cot=cos/sin.

D has no relation to any definition or identity.

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12

-12 > a

step-by-step explanation:

-11 > 1 + a

subtract 1 from each side

-11-1 > 1-1+a

-12 > a