A rectangle intersects a circle as shown: AB=4, BC=5, and DE=3. Then EF equals:
Answers
Where is the figure?
Answer:
For normal incidence on a plane mirror identify which of these statements are true --
(I) Both the angles of incidence and reflection are 0 degree .
(II) Both the angles of incidence and reflection are 90 degree .
(III) The angles that both the incident ray and the reflected ray make with the mirror surface are 0 degree .
(IV) The angles that both the incident ray and the reflected ray make with the mirror surface are 90 degree ..
A) Only (I) is true .
B) Only (II) is true .
C) Both (I) and (III) are true .
D) Both (I) and (IV) are true ✔
Answer:
Draw and , forming a trapezoid. Since it's cyclic, this trapezoid must be isosceles. Also, drop altitudes from to and to and let the feet of these altitudes be and respectively. is a rectangle since it has right angles. Therefore, and By the same logic, is also a rectangle, and . since they're both altitudes to a trapezoid, and since the trapezoid is isosceles. Therefore, by HL congruence, so Also, is a rectangle from right angles, and Therefore,